U.S. patent number 7,968,636 [Application Number 11/617,683] was granted by the patent office on 2011-06-28 for tire compositions and components containing silated cyclic core polysulfides.
This patent grant is currently assigned to Continental AG. Invention is credited to Richard W. Cruse, Janna Jaeckel, Prashant G. Joshi, Eric Raymond Pohl, W. Michael York.
United States Patent |
7,968,636 |
York , et al. |
June 28, 2011 |
Tire compositions and components containing silated cyclic core
polysulfides
Abstract
Sulfur-containing silane coupling agents, and organic polymers
containing carbon-carbon double bonds. These silanes can be carried
on organic and inorganic fillers. The invention also relates to
tire compositions and articles of manufacture, particularly tires,
made from the elastomer compositions described herein.
Inventors: |
York; W. Michael (Concord,
NC), Cruse; Richard W. (Yorktown Heights, NY), Jaeckel;
Janna (Hanover, DE), Pohl; Eric Raymond (Mt.
Kisco, NY), Joshi; Prashant G. (Gaithersburg, MD) |
Assignee: |
Continental AG (Hannover,
DE)
|
Family
ID: |
39584905 |
Appl.
No.: |
11/617,683 |
Filed: |
December 28, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080161462 A1 |
Jul 3, 2008 |
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Current U.S.
Class: |
524/262; 524/492;
524/495; 524/261 |
Current CPC
Class: |
C08L
9/06 (20130101); B60C 1/0016 (20130101); C08K
5/548 (20130101); C08L 21/00 (20130101); C08L
2666/08 (20130101); C08L 9/06 (20130101); C08K
5/548 (20130101); C08L 7/00 (20130101); C08L
9/00 (20130101); C08L 7/00 (20130101); C08L
9/00 (20130101); C08K 3/013 (20180101); C08K
5/548 (20130101); C08L 21/00 (20130101) |
Current International
Class: |
B60C
1/00 (20060101); C08K 5/24 (20060101); C08K
3/34 (20060101); C08K 3/04 (20060101) |
Field of
Search: |
;524/261,262,492,495 |
References Cited
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|
Primary Examiner: Eashoo; Mark
Assistant Examiner: Scott; Angela C
Attorney, Agent or Firm: Greenblum & Bernstein,
P.L.C.
Claims
What is claimed is:
1. A tire composition for forming a tire component, the composition
formed by combining at least: (a) a silated cyclic core polysulfide
of the general formula
[Y.sup.1R.sup.1S.sub.x--].sub.m[G.sup.1(SR.sup.2SiX.sup.1X.sup.2X.sup.3).-
sub.a].sub.n[G.sup.2].sub.o[R.sup.3Y.sup.2].sub.p wherein: each
occurrence of G.sup.1 is independently selected from a polyvalent
hydrocarbon species having from 1 to about 30 carbon atoms
containing a polysulfide group represented by the general formula:
[(CH.sub.2).sub.b--].sub.cR.sup.4[--(CH.sub.2).sub.dS.sub.x--].sub.e;
each occurrence of G.sup.2 is independently selected from a
polyvalent hydrocarbon species of 1 to about 30 carbon atoms
containing a polysulfide group represented by the general formula:
[(CH.sub.2).sub.b--].sub.cR.sup.5[--(CH.sub.2).sub.dS.sub.x--].sub.e;
each occurrence of R.sup.1 and R.sup.3 is independently selected
from a divalent hydrocarbon fragment having from 1 to about 20
carbon atoms; each occurrence of Y.sup.1 and Y.sup.2 is
independently selected from silyl (--SiX.sup.1X.sup.2X.sup.3),
alkoxy (--OR.sup.6), hydrogen, carboxylic acid, and ester
(--C(.dbd.O)OR.sup.6) wherein R.sup.6 is a monovalent hydrocarbon
group having from 1 to 20 carbon atoms; each occurrence of R.sup.2
is independently selected from divalent hydrocarbon fragment having
from 1 to 20 carbon atoms; each occurrence of R.sup.4 is
independently selected from a polyvalent cyclic hydrocarbon
fragment of 1 to about 28 carbon atoms or a polyvalent cyclic
heterocarbon fragment of 1 to about 27 carbon atoms that was
obtained by substitution of hydrogen atoms equal to the sum of
a+c+e; each occurrence of R.sup.5 is independently selected from a
polyvalent hydrocarbon fragment of 1 to about 28 carbon atoms or a
polyvalent cyclic heterocarbon fragment of 1 to about 27 carbon
atoms that was obtained by substitution of hydrogen atoms equal to
the sum of c+e; each occurrence of X.sup.1 is independently
selected from --Cl, --Br, --OH, --OR.sup.6, and
R.sup.6C(.dbd.O)O--, wherein R.sup.6 is a monovalent hydrocarbon
group having from 1 to 20 carbon atoms; each occurrence of X.sup.2
and X.sup.3 is independently selected from hydrogen, R.sup.6,
wherein R.sup.6 is a monovalent hydrocarbon group having from 1 to
20 carbon atoms, X.sup.1, wherein X.sup.1 is independently selected
from --Cl, --Br, --OH, --OR.sup.6, and R.sup.6C(.dbd.O)O--, wherein
R.sup.6 is a monovalent hydrocarbon group having from 1 to 20
carbon atoms, and --OSi containing groups that result from the
condensation of silanols; and each occurrence of the subscripts, a,
b, c, d, e, m, n, o, p, and x, is independently given wherein a, c
and e are 1 to about 3; b is 1 to about 5; d is 1 to about 5; m and
p are 1 to about 100; n is 1 to about 15; o is 0 to about 10; and x
is 1 to about 10; (b) at least one vulcanizable rubber selected
from natural rubbers, synthetic polyisoprene rubbers,
polyisobutylene rubbers, polybutadiene rubbers, and random
styrene-butadiene rubbers (SBR); and (c) an active filler including
at least one of active filler selected from carbon blacks, silicas,
silicon based fillers, and metal oxides present in a combined
amount of at least 35 parts by weight per 100 parts by weight of
total vulcanizable rubber, of which at least 10 parts by weight is
carbon black, silica, or a combination thereof; and wherein the
tire composition is formulated to be vulcanizable to form a tire
component compound having a Shore A Hardness of not less than 40
and not greater than 95 and a glass-transition temperature Tg
(E''.sub.max) not less than -80.degree. C. and not greater than
0.degree. C.
2. The tire composition of claim 1 wherein R.sup.1 and R.sup.3 are
branched or straight chain alkyl, alkenyl, alkynyl, aryl or aralkyl
groups in which one hydrogen atom is substituted with a Y.sup.1 or
Y.sup.2 group.
3. The tire composition of claim 1 wherein R.sup.6 is branched or
straight chain alkyl, alkenyl, aryl or aralkyl.
4. The tire composition of claim 1 wherein R.sup.4 is cyclic or
polycyclic alkyl, alkenyl, alkynyl, aryl, or aralkyl in which
a+c+e-1 hydrogens have been replaced.
5. The tire composition of claim 1 wherein R.sup.4 and R.sup.5 are
polyvalent heterocarbon fragments from 1 to 27 carbon atoms.
6. The tire composition of claim 1 wherein R.sup.5 is cyclic or
polycyclic alkyl, alkenyl, alkynyl, aryl, or aralkyl in which
a+c+e-1 hydrogens have been replaced.
7. The tire composition of claim 6 wherein the heteroatom of
R.sup.4 and R.sup.5 is selected from sulfur, oxygen, nitrogen, and
mixtures thereof.
8. The tire composition of claim 1 wherein the cyclic or polycyclic
alkyl, alkynyl, aryl, aralkyl and arenyl of R.sup.4 in which
a+c+e-1 hydrogens have been replaced is selected from ethylidenyl
norbornane, ethylidene norbornyl, ethylidenyl norbornene,
ethylidene norbornenyl, phenyl, naphthalenyl, benzyl, phenethyl,
tolyl, xylyl, norbornyl, norbornenyl, ethylnorbornyl,
ethylnorbornenyl, cyclohexyl, ethylcyclohexyl, ethylcyclohexenyl,
cyclohexylcyclohexyl, and cyclododecatrienyl.
9. The tire composition of claim 1 wherein the cyclic alkyl,
alkynyl, aryl, aralkyl and arenyl of R.sup.5 in which c+e-1
hydrogens have been replaced is selected from ethylidenyl
norbornane, ethylidene norbornyl, ethylidenyl norbornene,
ethylidene norbornenyl, phenyl, naphthalenyl, benzyl, phenethyl,
tolyl, xylyl, norbornyl, norbornenyl, ethylnorbornyl,
ethylnorbornenyl, cyclohexyl, ethylcyclohexyl, ethylcyclohexenyl,
cyclohexylcyclohexyl, and cyclododecatrienyl.
10. The tire composition of claim 1 wherein cyclic structure of
R.sup.4, R.sup.5, and R.sup.6 is selected from bicyclic, tricyclic,
higher cyclic structures, cyclic structures substituted with alkyl,
alkenyl, and/or alkynyl groups.
11. The tire composition of claim 1 wherein X.sup.1 is selected
from methoxy, ethoxy, propoxy, isopropoxy, butoxy, phenoxy,
benzyloxy, hydroxy, chloro, and acetoxy.
12. The tire composition of claim 1 wherein X.sup.2 and X.sup.3 are
selected from methoxy, ethoxy, propoxy, isopropoxy, butoxy,
phenoxy, benzyloxy, hydroxy, chloro, acetoxy, hydrogen, methyl,
ethyl, propyl, isopropyl, sec-butyl, phenyl, vinyl, cyclohexyl,
straight-chain alkyl, butyl, hexyl, octyl, lauryl, and
octadecyl.
13. The tire composition of claim 1 wherein R.sup.1 and R.sup.3 are
terminal straight-chain alkyls substituted terminally at the end
with --CH.sub.2--, --CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2--,
beta-substituted analogs, and mixtures thereof.
14. The tire composition of claim 13 wherein the beta substituted
analog is --CH.sub.2(CH.sub.2).sub.uCH(CH.sub.3)--, where u is zero
to 17.
15. The tire composition of claim 13 wherein R.sup.1 and R.sup.3
are structures derived from methallyl chloride, divinylbenzene,
diallylether, butadiene, piperylene, isoprene, diradicals,
limonene, monovinyl-containing structures derived from
trivinylcyclohexane, monounsaturated structures derived from
myrcene containing a trisubstituted C.dbd.C, monounsaturated
structures derived from myrcene lacking a trisubstituted C.dbd.C,
and mixtures thereof.
16. The tire composition of claim 1 wherein G.sup.1 is selected
from structures derivable from divinylbenzene, and comprises
--CH.sub.2CH.sub.2(C.sub.6H.sub.4)CH(CH.sub.2--)--,
--CH.sub.2CH.sub.2(C.sub.6H.sub.3--)CH.sub.2CH.sub.2--, or
--CH.sub.2(CH--)(C.sub.6H.sub.4)CH(CH.sub.2--)--, where the
notation C.sub.6H.sub.4 denotes a disubstituted benzene ring and
C.sub.6H.sub.3-- denotes a trisubstituted ring.
17. The tire composition of claim 1 wherein G.sup.1 is derived from
trivinylcyclohexane, and comprises
--CH.sub.2(CH--)(vinylC.sub.6H.sub.9)CH.sub.2CH.sub.2--,
(--CH.sub.2CH.sub.2).sub.3C.sub.6H.sub.9,
(--CH.sub.2CH.sub.2).sub.2C.sub.6H.sub.9CH(CH.sub.3)--,
--CH.sub.2(CH--)(vinylC.sub.6H.sub.9)(CH--)C.sub.2--,
--CH.sub.2CH.sub.2C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.2,
--CH(CH.sub.3)C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.2,
C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.3,
--CH.sub.2(CH--)C.sub.6H.sub.9[CH.sub.2CH.sub.2--].sub.2, or
--CH.sub.2(CH--)
C.sub.6H.sub.9[CH(CH.sub.3)--][CH.sub.2CH.sub.2--], where the
notation C.sub.6H.sub.9 denotes any isomer of the trisubstituted
cyclohexane ring.
18. The tire composition of claim 1 wherein G.sup.2 is derived from
divinylbenzene, and comprises
--CH.sub.2CH.sub.2(C.sub.6H.sub.4)CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2(C.sub.6H.sub.4)CH(CH.sub.2--)--,
--CH.sub.2CH.sub.2(C.sub.6H.sub.3--)CH.sub.2CH.sub.2--, or
--CH.sub.2(CH--)(C.sub.6H.sub.4)CH(CH.sub.2--)--, where the
notation C.sub.6H.sub.4 denotes a disubstituted benzene ring and
C.sub.6H.sub.3-- denotes a trisubstituted ring.
19. The tire composition of claim 1 wherein G.sup.2 is selected
from structures derivable from trivinylcyclohexane, and comprises
--CH.sub.2CH.sub.2(vinylC.sub.6H.sub.9)CH.sub.2CH.sub.2--,
(--CH.sub.2CH.sub.2)C.sub.6H.sub.9CH.sub.2CH.sub.3,
--CH.sub.2(CH--)(vinylC.sub.6H.sub.9)CH.sub.2CH.sub.2--,
(--CH.sub.2CH.sub.2).sub.3C.sub.6H.sub.9,
(--CH.sub.2CH.sub.2).sub.2C.sub.6H.sub.9CH(CH.sub.3)--,
--CH.sub.2(CH--)(vinylC.sub.6H.sub.9)(CH--)CH.sub.2--,
--CH.sub.2CH.sub.2C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.2,
--CH(CH.sub.3)C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.2,
C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.3,
--CH.sub.2(CH--)C.sub.6H.sub.9[CH.sub.2CH.sub.2--].sub.2, or
--CH.sub.2(CH--)C.sub.6H.sub.9[CH(CH.sub.3)--][CH.sub.2CH.sub.2--],
where the notation C.sub.6H.sub.9 denotes any isomer of the
trisubstituted cyclohexane ring.
20. The tire composition of claim 1 wherein the silated cyclic core
polysulfide is any of the isomers of
4-(6-triethoxysilyl-3-thiahexyl)-1,2-bis-(13-triethoxysilyl-3,4,5,6-tetra-
thiatridecyl)cyclohexane;
4-(6-triethoxysilyl-3-thiahexyl)-1,2-bis-(13-triethoxysilyl-3,4-dithiatri-
decyl)cyclohexane;
4-(6-triethoxysilyl-3-thiahexyl)-1,2-bis-(13-triethoxysilyl-3,4,5-trithia-
tridecyl)cyclohexane;
4-(6-triethoxysilyl-3-thiahexyl)-1,2-bis-(12-triethoxysilyl-3,4,5-tetrath-
iadodecyl)cyclohexane;
1-(6-triethoxysilyl-3-thiahexyl)-2,4-bis-(11-triethoxysilyl-3,4-tetrathia-
unidecyl)cyclohexane;
4-(3-triethoxysilyl-1-thiaethyl)-1,2-bis-(13-triethoxysilyl-3,4,5,6,7-pen-
tathiamidecyl)cyclohexane; 4-(6-diethoxymethylsilyl-2-thia
hexyl)-1,2-bis-(13-triethoxysilyl-3,4,5,6-tetrathiatridecyl)cyclohexane;
4-(4-triethoxysilyl-2-thiabutyl)-1,2-bis-(9-triethoxysilyl-3,4,5,6-tetrat-
hianonyl)cyclohexane;
4-(7-triethoxysilyl-3-thiaheptyl)-1,2-bis-(9-triethoxysilyl-3,4,5-trithia-
nonyl)cyclohexane;
4-(5-triethoxysilyl-2-thiapentyl)-1,2-bis-(9-triethoxysilyl-3,4,5,6-tetra-
thianonyl)benzene;
4-(5-triethoxysilyl-2-thiapentyl)-1,2-bis-(9-triethoxysilyl-3,4,5-trithia-
nonyl)benzene;
4-(5-triethoxysilyl-2-thiapentyl)-1,2-bis-(9-triethoxysilyl-3,4-dithianon-
yl)benzene;
bis-2-[4-(3-triethoxysilyl-2-thiapropyl)-3-(9-triethoxysilyl-3,4,5,6-tetr-
athianonyl)cyclohexyl]ethyl tetrasulfide;
bis-2-[4-(3-triethoxysilyl-1-thiapropyl)-3-(9-triethoxysilyl-3,4,5,6-tetr-
athianonyl)cyclohexyl]ethyl trisulfide;
bis-2-[4-(3-triethoxysilyl-1-thiapropyl)-3-(7-triethoxysilyl-3,4-dithiahe-
ptyl)cyclohexyl]ethyl disulfide;
bis-2-[4-(6-triethoxysilyl-3-thiahexyl)-3-(9-triethoxysilyl-3,4,5-trithia-
nonyl)phenyl]ethyl tetrasulfide;
bis-2-[4-(6-triethoxysilyl-3-thiahexyl)-3-(9-triethoxysilyl-3,4,5-trithia-
nonyl)nathyl]ethyl tetrasulfide;
bis-2-[4-(4-diethoxymethylsilyl-2-thiabutyl)-3-(9-triethoxysilyl-3,4,5,6--
tetrathianonyl)phenyl]ethyl trisulfide;
bis-2-[4-(4-triethoxysilyl-2-thiaethyl)-3-(7-triethoxysilyl-3,4-dithiahep-
tyl)cycloheptyl]ethyl disulfide;
bis-2-[4-(4-triethoxysilyl-2-thiaethyl)-3-(7-triethoxysilyl-3,4-dithiahep-
tyl)cyclooctyl]ethyl disulfide;
bis-2-[4-(4-triethoxysilyl-2-thiaethyl)-3-(7-triethoxysilyl-3,4-dithiahep-
tyl)cyclododecyl]ethyl disulfide, 4-(6-triethoxysilyl-3-thiahexyl)
-1,2-bis-(9-triethoxysilyl-3,4,5,6-tetrathianonyl)cyclohexane;
2-(6-triethoxysilyl-3-thiahexyl)-1,4-bis-(9-triethoxysilyl-3,4,5,6-tetrat-
hianonyl)cyclohexane;
1-(6-triethoxysilyl-3-thiahexyl)-2,4-bis-(9-triethoxysilyl-3,4,5,6-tetrat-
hianonyl)cyclohexane;
4-(6-triethoxysilyl-3-thiahexyl)-1,2-bis-(7-triethoxysilyl-3,4-dithiahept-
yl)cyclohexane;
2-(6-triethoxysilyl-3-thiahexyl)-1,4-bis-(7-triethoxysilyl-3,4-dithiahept-
yl)cyclohexane;
1-(6-triethoxysilyl-3-thiahexyl)-2,4-bis-(7-triethoxysilyl-3,4-dithiahept-
yl)cyclohexane; and mixtures thereof.
21. The tire composition of claim 1 wherein R.sup.1 and R.sup.3 are
independently selected from a divalent hydrocarbon fragment having
from 1 to about 5 carbon atoms.
22. The tire composition of claim 21 wherein R.sup.1 and R.sup.3
are branched and/or straight chain alkyl, alkenyl or alkynyl groups
in which one hydrogen atom is substituted with a Y.sup.1 or Y.sup.2
group.
23. The tire composition of claim 21 wherein Y.sup.1 and Y.sup.2
are silyl (--SiX.sup.1, X.sup.2, X.sup.3), hydrogen, alkoxy
(--OR.sup.6), carboxylic acid, ester (--C(.dbd.O)OR.sup.6) wherein
R.sup.6 is a monovalent hydrocarbon group having from 1 to 5 carbon
atoms.
24. The tire composition of claim 21 wherein R.sup.2 is a straight
chain hydrocarbon represented by --(CH.sub.2).sub.f-- where f is an
integer from about 1 to about 5.
25. The tire composition of claim 21 wherein R.sup.4 is a
polyvalent hydrocarbon fragment of 5 to about 12 carbon atoms.
26. The tire composition of claim 21 wherein R.sup.5 is a
polyvalent hydrocarbon fragment of 5 to about 12 carbon atoms.
27. The tire composition of claim 21 wherein X.sup.1 is
independently selected from hydrolysable --OH, and --OR.sup.6,
wherein R.sup.6 is a monovalent hydrocarbon group having from 1 to
5 carbon atoms.
28. The tire composition of claim 21 wherein X.sup.2 and X.sup.3
are independently selected from R.sup.6, wherein R.sup.6 is a
monovalent hydrocarbon group having from 1 to 5 carbon atoms,
X.sup.1, wherein X.sup.1 is independently selected from
hydrolysable --OH, --OR.sup.6, wherein R.sup.6 is a monovalent
hydrocarbon group having from 1 to 5 carbon atoms, and --OSi
containing groups that result from the condensation of
silanols.
29. The tire composition of claim 27 wherein each occurrence of the
subscripts, a, b, c, d, e, f, m, n, o, p, and x, is independently
given by a is 1 to about 2; b and d are 1 to about 3; c and e are
1; f is 1 to about 5; m and p are 1, n is 1 to about 10; o is 0 to
about 1; and x is 1 to about 6.
30. A tire composition formed by combining from about 30 to about
99 weight percent of the tire composition of claim 1 and about 70
to about 1 weight percent of a silane of the general formula:
[X.sup.1X.sup.2X.sup.3SiR.sup.1S.sub.xR.sup.3SiX.sup.1X.sup.2X.sup.3]
wherein each occurrence of R.sup.1 and R.sup.3 is independently
selected from a divalent hydrocarbon fragment having from 1 to
about 20 carbon atoms that include branched and straight chain
alkyl, alkenyl, alkynyl, aryl or aralkyl groups wherein one
hydrogen atom was substituted with a (--SiX.sup.1X.sup.2X.sup.3)
group; each occurrence of X.sup.1 is independently selected from
--Cl, --Br, --OH, --OR.sup.6, and R.sup.6C(.dbd.O)O--, wherein
R.sup.6 is a monovalent hydrocarbon group having from 1 to 20
carbon atoms, and includes branched or straight chain alkyl,
alkenyl, aryl or aralkyl group; and each occurrence of X.sup.2 and
X.sup.3 is independently selected from hydrogen, R.sup.6, X.sup.1,
and --OSi containing groups that result from the condensation of
silanols; and x is 1 to about 10.
31. The tire composition of claim 30 wherein the silane is selected
from bis-(3-triethoxysilylpropyl) disulfide;
bis-(3-triethoxysilylpropyl) trisulfide;
bis-(3-triethoxysilylpropyl) tetrasulfide;
bis-(3-triethoxysilylpropyl) pentasulfide;
bis-(3-diethoxymethylsilylpropyl) disulfide;
bis-(3-ethoxydimethylsilylpropyl) disulfide;
bis-(triethoxysilylmethyl) disulfide; bis-(4-triethoxysilylbenzyl)
disulfide, bis-(3-triethoxysilylphenyl) disulfide, and mixtures
thereof.
32. The tire composition of claim 1, further comprising curative
and, optionally, at least one other additive selected from sulfur
compounds, activators, retarders, accelerators, processing
additives, oils, plasticizers, tackifying resins, silicas, fillers,
pigments, fatty acids, zinc oxide, waxes, antioxidants and
antiozonants, peptizing agents, reinforcing materials, and mixtures
thereof.
33. The tire composition of claim 1, wherein the at least one
vulcanizable rubber is at least one natural rubber.
34. The tire composition of claim 1, wherein the at least one
vulcanizable rubber is at least one emulsion polymerization derived
rubber.
35. The tire composition of claim 1, wherein the at least one
vulcanizable rubber is at least one solvent polymerization derived
rubber.
36. The tire composition of claim 35, wherein the solvent
polymerization derived rubber is styrene/butadiene rubber
containing from about 5 to about 50 percent vinyl content.
37. The tire composition of claim 35, wherein the solvent
polymerization derived rubber is styrene/butadiene rubber
containing from about 9 to about 36 percent vinyl content.
38. The tire composition of claim 1, wherein the at least one
vulcanizable rubber is prepared from conjugated diene selected from
isoprene, 1,3-butadiene, styrene, and alpha methyl styrene, and
mixtures thereof.
39. The tire composition of claim 1, wherein the at least one
vulcanizable rubber is formed from polybutadiene of which about 90
weight percent is in the cis-1,4-butadiene form.
40. The tire composition of claim 1, wherein the at least one
vulcanizable rubber is selected from cis-1,4-polyisoprene rubber,
emulsion polymerization prepared styrene/butadiene copolymer
rubber, organic solution polymerization prepared styrene/butadiene
rubber, 3,4-polyisoprene rubber, isoprene/butadiene rubber,
styrene/isoprene/butadiene terpolymer rubber,
cis-1,4-polybutadiene, medium vinyl polybutadiene rubber, wherein
the medium vinyl polybutadiene rubber has about 35 to 50 weight
percent vinyl, high vinyl polybutadiene rubber wherein the high
vinyl polybutadiene rubber has about 50 to 75 weight percent vinyl,
styrene/isoprene copolymers, emulsion polymerization prepared
styrene/butadiene/acrylonitrile terpolymer rubber and
butadiene/acrylonitrile copolymer rubber.
41. The tire composition of claim 40 wherein the emulsion
polymerization derived styrene/butadiene has a styrene content of
about 20 to about 28 weight percent.
42. The tire composition of claim 41 wherein the emulsion
polymerization derived styrene/butadiene has a styrene content of
about 30 to about 45 weight percent.
43. The tire composition of claim 1 wherein the at least one
vulcanizable rubber comprises emulsion polymerization prepared
styrene/butadiene/acrylonitrile terpolymer rubber containing from
about 2 to about 40 weight percent acrylonitrile.
44. The tire composition of claim 1 wherein the total amount of
silated cyclic core polysulfide present in the rubber composition
is from about 0.05 to about 25 parts by weight per hundred parts by
weight of rubber.
45. The tire composition of claim 1 wherein the total amount of
silated cyclic core polysulfide present in the rubber composition
is from about 1 to about 10 parts by weight per hundred parts by
weight of rubber.
46. The tire composition according to claim 1 wherein the silated
cyclic core polysulfide comprises any isomer of
(6-triethoxysilyl-3-thia-1-hexyl)-bis-(7-triethoxysilyl-3,4-dithiaheptyl)-
cyclohexane.
47. The tire composition according to claim 1 wherein the silated
cyclic core polysulfide comprises any isomer of
(6-triethoxysilyl-3-thia-1-hexyl)-bis-(9-triethoxysilyl-3,4,5,6-tetrathia-
nonyl)cyclohexane.
48. A tire at least one component of which comprises a cured tire
composition obtained from the tire composition of claim 1.
49. A tire tread which comprises a cured tire composition obtained
from the tire composition of claim 1.
50. A tire component comprising a cured tire composition obtained
from the tire composition of claim 1.
51. An uncured tire component comprising a tire composition
obtained from the tire composition of claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is related to the following applications,
filed on even date herewith, with the disclosures of each the
applications being incorporated by reference herein in their
entireties:
Application Ser. No. 11/617,663, filed Dec. 28, 2006, entitled Tire
Compositions And Components Containing Silated Core
Polysulfides.
Application Ser. No. 11/617,649, filed Dec. 28, 2006, entitled Tire
Compositions And Components Containing Free-Flowing Filler
Compositions.
Application Ser. No. 11/617,678, filed Dec. 28, 2006, entitled Tire
Compositions And Components Containing Free-Flowing Filler
Compositions.
Application Ser. No. 11/617,659, filed Dec. 28, 2006, entitled Tire
Compositions and Components Containing Blocked Mercaptosilane
Coupling Agent.
Application Ser. No. 11/648,460, filed Dec. 28, 2006, entitled
Free-Flowing Filler Composition And Rubber Composition Containing
Same.
Application Ser. No. 11/647,903, filed Dec. 28, 2006, entitled
Free-Flowing Filler Composition And Rubber Composition Containing
Same.
Application Ser. No. 11/647,780, filed Dec. 28, 2006, entitled
Blocked Mercaptosilane Coupling Agents, Process For Making And Uses
In Rubber.
Application Ser. No. 11/648,287, filed Dec. 28, 2006, entitled
Silated Core Polysulfides, Their Preparation And Use In Filled
Elastomer Compositions.
Application Ser. No. 11/647,901, filed Dec. 28, 2006, entitled
Silated Cyclic Core Polysulfides, Their Preparation And Use In
Filled Elastomer Compositions.
The present application is directed to an invention which was
developed pursuant to a joint research agreement within the meaning
of 35 U.S.C. .sctn.103(c). The joint research agreement dated May
7, 2001 as amended, between Continental AG, and General Electric
Company, on behalf of GE Advanced Materials, Silicones Division,
now Momentive Performance Materials Inc.
FIELD OF THE INVENTION
The present invention generally relates to silated cyclic core
polysulfides compositions, processes for their preparation, and
tire compositions and tire components comprising the same.
BACKGROUND OF THE INVENTION
Sulfur-containing coupling agents used for mineral-filled
elastomers involve silanes in which two alkoxysilylalkyl groups are
bound, each to one end of a chain of sulfur atoms. The two
alkoxysilyl groups are bonded to the chain of sulfur atoms by two
similar, and in most cases, identical, hydrocarbon fragments. The
general silane structures just described, hereinafter referred to
as "simple bis polysulfide silanes," usually contain a chain of
three methylene groups as the two mediating hydrocarbon units. In
some cases, the methylene chain is shorter, containing only one or
two methylenes per chain. The use of these compounds is primarily
as coupling agents for mineral-filled elastomers. These coupling
agents function by chemically bonding silica or other mineral
fillers to polymer when used in rubber applications. Coupling is
accomplished by chemical bond formation between the silane sulfur
and the polymer and by hydrolysis of the alkoxysilyl groups and
subsequent condensation with silica hydroxyl groups. The reaction
of the silane sulfur with the polymer occurs when the S--S bonds
are broken and the resulting fragment adds to the polymer. A single
linkage to the polymer occurs for each silyl group bonded to the
silica. This linkage contains a single, relatively weak C--S and/or
S--S bond(s) that forms the weak link between the polymer and the
silica. Under high stress, this single C--S and/or S--S linkages
may break and therefore contribute to wear of the filled
elastomer.
The use of polysulfide silanes coupling agents in the preparation
of rubber is well known. These silanes contain two silicon atoms,
each of which is bound to a disubstituted hydrocarbon group, and
three other groups of which at least one is removable from silicon
by hydrolysis. Two such hydrocarbon groups, each with their bound
silyl group, are further bound to each end of a chain of at least
two sulfur atoms. These structures thus contain two silicon atoms
and a single, continuous chain of sulfur atoms of variable
length.
Hydrocarbon core polysulfide silanes that feature a central
molecular core isolated from the silicon in the molecule by
sulfur-sulfur bonds are known in the art. Polysulfide silanes
containing a core that is an aminoalkyl group separated from the
silicon atom by a single sulfur and a polysulfide group and where
the polysulfide group is bonded to the core at a secondary carbon
atom are also known in the art. As well as core fragments in which
only two polysulfide groups are attached to the core.
When the polysulfide groups are attached directly to an aromatic
core, the reactivity with the polymer (rubber) is reduced. The
aromatic core is sterically bulky which inhibits the reaction.
Compositions in which the polysulfides are attached directly to
cyclic aliphatic fragments derived by vinyl cyclohexene contain
more than one silated core and form large rings. The cyclohexyl
core is sterically more hindered than the aromatic core and is less
reactive. Although these compositions can form more than one sulfur
linkage to the polymer rubber for each attachment of the coupling
agent to the silica through the silyl group, their effectiveness is
low due to the low reactivity.
The low reactivity is due to the attachment of the polysulfide to
the secondary carbon of cyclic core structure. The positioning of
the polysulfide group is not optimal for reaction with the
accelerators and reaction with the polymer.
The present invention overcomes the deficiencies of the
aforementioned compositions involving silane coupling agents in
several ways. The silanes of the present invention described herein
are not limited to two silyl groups nor to one chain of sulfur
atoms. In fact the molecular architecture in which multiple
polysulfide chains are oriented in a noncollinear configuration
(i.e. branched, in the sense that the branch points occur within
the carbon backbone interconnecting the polysulfide chains) is
novel.
The silanes of the present invention have advantages over that in
the prior art by providing multiple points of sulfur attachment to
polymer per point of silicon attachment to filler. The silanes
described herein may be asymmetric with regard to the groups on the
two ends of the sulfur chains. The silyl groups, rather than
occurring at the ends of the molecule, tend to occur more centrally
and are chemically bonded to the cyclic core through carbon-carbon,
carbon-sulfur and carbon-silicon bonds. The carbon-sulfur bonds of
the thio ester linkages (sulfide) are more stable than the
sulfur-sulfur bonds of the disulfide or polysulfide functional
groups. These thio ether groups are therefore less likely to react
with the accelerators and curing agents or to decompose when
subjected to high shear or temperatures normally associated with
the mixing and curing of rubber compounds. The thio ether linkage
also provides a convenient synthetic route for making the silanes
of the present invention. The cyclic core also contains multiple
polysulfide groups that are attached to ring by a divalent,
straight chain alkylene group. The attachment of the polysulfide
group to the primary carbon of the alkylene group decreases
significantly the steric hindrance of the core, and increases the
reactivity of the polysulfides with the polymer. In addition, the
cyclic core orients these alkylene chains containing the
polysulfide groups away from each other to further reduce the
steric hindrance near the polysulfide groups. This distinction is
what allows silica to become and remain bonded (through the
intermediacy of a sequence of covalent chemical bonds) to polymer
at multiple points using the silanes of the present invention.
Also, without being bound by theory, silated core silanes of the
present invention include a Y-core structure. This Y-core structure
is believed to enable bonding the polymer at two different points
or crosslinking on two different polymer chains, and also enables
attachment, such as by bonding, to a filler.
The examples presented herein demonstrate that the silanes of the
present invention impart a desirable balance of physical properties
(performance to mineral-filled elastomer compositions) and better
wear characteristics to articles manufactured from these
elastomers. Improvements in rolling resistance are also apparent
for elastomers used in tire applications.
SUMMARY OF THE INVENTION
In a first embodiment of the present invention, silated cyclic core
polysulfides of the present invention can be represented by Formula
(1)
[Y.sup.1R.sup.1S.sub.x--].sub.m[G.sup.1(SR.sup.2SiX.sup.1X.sup.2X.sup.3).-
sub.a].sub.n[G.sup.2].sub.o[R.sup.3Y.sup.2].sub.p (1) wherein each
occurrence of G.sup.1 is independently selected from polyvalent
cyclic hydrocarbon or heterocarbon species having from 1 to about
30 carbon atoms and containing a polysulfide group represented by
Formula (2)
[(CH.sub.2).sub.b--].sub.cR.sup.4[--(CH.sub.2).sub.dS.sub.x--].sub.e;
(2) each occurrence of G.sup.2 is independently selected from a
polyvalent cyclic hydrocarbon or heterocarbon species of 1 to about
30 carbon atoms and containing a polysulfide group represented by
Formula (3)
[(CH.sub.2).sub.b--].sub.cR.sup.5[--(CH.sub.2).sub.dS.sub.x--].sub.e;
(3) each occurrence of R.sup.1 and R.sup.3 are independently
selected from a divalent hydrocarbon fragment having from 1 to
about 20 carbon atoms that include branched and straight chain
alkyl, alkenyl, alkynyl, aryl or aralkyl groups in which one
hydrogen atom was substituted with a Y.sup.1 or Y.sup.2 group;
each occurrence of Y.sup.1 and Y.sup.2 is independently selected
from, but not limited to silyl (--SiX.sup.1X.sup.2X.sup.3), alkoxy
(--OR.sup.6), hydrogen, carboxylic acid (--C(.dbd.O)OH), ester
(--C(.dbd.O)OR.sup.6), in which R.sup.6 is any monovalent
hydrocarbon group having from 1 to 20 carbon atoms, and includes
branched or straight chain alkyl, alkenyl, aryl or aralkyl groups,
and the like;
each occurrence of R.sup.2 is independently selected from a
divalent hydrocarbon fragment having from 1 to about 20 carbon
atoms that include branched and straight chain alkyl, alkenyl,
alkynyl, aryl or aralkyl groups;
each occurrence of R.sup.4 is independently selected from a
polyvalent cyclic hydrocarbon fragment of 1 to about 28 carbon
atoms that was obtained by substitution of hydrogen atoms equal to
the sum of a+c+e, and include cyclic and polycyclic alkyl, alkenyl,
alkynyl, aryl and aralkyl groups in which a+c+e-1 hydrogens have
been replaced, or a polyvalent cyclic heterocarbon fragment from 1
to 27 carbon atoms that was obtained by substitution of hydrogen
atoms equal to the sum of a+c+e;
each occurrence of R.sup.5 is independently selected from a
polyvalent cyclic hydrocarbon fragment of 1 to about 28 carbon
atoms that was obtained by substitution of hydrogen atoms equal to
the sum of c+e, and include cyclic and polycyclic alkyl, alkenyl,
alkynyl, aryl and aralkyl groups in which c+e-1 hydrogens have been
replaced, or a polyvalent cyclic heterocarbon fragment from 1 to 27
carbon atoms that was obtained by substitution of hydrogen atoms
equal to the sum of c+e;
each occurrence of X.sup.1 is independently selected from
hydrolysable groups selected from --Cl, --Br, --OH, --OR.sup.6, and
R.sup.6C(.dbd.O)O--, wherein R.sup.6 is any monovalent hydrocarbon
group having from 1 to 20 carbon atoms, and includes branched or
straight chain alkyl alkenyl, aryl or aralkyl groups;
each occurrence of X.sup.2 and X.sup.3 is independently selected
from hydrogen, any of R.sup.6 as listed above, any of X.sup.1 as
listed above and --OSi containing groups that result from the
condensation of silanols;
each occurrence of the subscripts, a, b, c, d, e, m, n, o, p, and
x, is independently given by a is 1 to about 3; b is 1 to about 5;
c is 1 to about 3; d is 1 to about 5; e is 1 to about 3; m is 1 to
about 100, n is 1 to about 15; o is 0 to about 10; p is 1 to about
100, and x is 1 to about 10.
In a second embodiment of the present invention, a process is
provided for the preparation of the silated cyclic core polysulfide
composition comprising reacting a cyclic hydrocarbon or cyclic
heterocarbon containing vinyl groups with a thioacid, the acyl
group is removed, and the mercapto groups are reacted with base and
a halo containing hydrocarbon silane and finally base, sulfur and a
halo containing substituted hydrocarbon.
In accordance with a third embodiment of the present invention, a
rubber composition is provided comprising (a) a silated cyclic core
polysulfide composition having the general Formula (1):
[Y.sup.1R.sup.1S.sub.x--].sub.m[G.sup.1(SR.sup.2SiX.sup.1X.sup.2X.sup.3).-
sub.a].sub.n[G.sup.2].sub.o[R.sup.3Y.sup.2].sub.p (1)
wherein Y.sup.1, R.sup.1, G.sup.1, R.sup.2,. X.sup.1, X.sup.2,
X.sup.3, G.sup.2, R.sup.2, Y.sup.2, a, o, p, x, m, and n have the
aforestated meanings; (b) an inorganic filler; and (c) a
rubber.
The present invention is also directed to a tire composition for
forming a tire component, the composition formed by combining at
least:
(a) a silated cyclic core polysulfide of the general formula
[Y.sup.1R.sup.1S.sub.x--].sub.m[G.sup.1(SR.sup.2SiX.sup.1X.sup.2X.sup.3).-
sub.a].sub.n[G.sup.2].sub.o[R.sup.3Y.sup.2].sub.p
wherein:
each occurrence of G.sup.1 is independently selected from a
polyvalent hydrocarbon species having from 1 to about 30 carbon
atoms containing a polysulfide group represented by the general
formula:
[(CH.sub.2).sub.b--].sub.cR.sup.4[--(CH.sub.2).sub.dS.sub.x--].sub.e;
each occurrence of G.sup.2 is independently selected from a
polyvalent hydrocarbon species of 1 to about 30 carbon atoms
containing a polysulfide group represented by the general formula:
[(CH.sub.2).sub.b--].sub.cR.sup.5[--(CH.sub.2).sub.dS.sub.x--].sub.e;
each occurrence of R.sup.1 and R.sup.3 is independently selected
from a divalent hydrocarbon fragment having from 1 to about 20
carbon atoms;
each occurrence of Y.sup.1 and Y.sup.2 is independently selected
from silyl (--SiX.sup.1X.sup.2X.sup.3), alkoxy (--OR.sup.6),
hydrogen, carboxylic acid, and ester (--C(.dbd.O)OR.sup.6) wherein
R.sup.6 is a monovalent hydrocarbon group having from 1 to 20
carbon atoms;
each occurrence of R.sup.2 is independently selected from divalent
hydrocarbon fragment having from 1 to 20 carbon atoms;
each occurrence of R.sup.4 is independently selected from a
polyvalent cyclic hydrocarbon fragment of 1 to about 28 carbon
atoms or a polyvalent cyclic heterocarbon fragment of 1 to about 27
carbon atoms that was obtained by substitution of hydrogen atoms
equal to the sum of a+c+e;
each occurrence of R.sup.5 is independently selected from a
polyvalent hydrocarbon fragment of 1 to about 28 carbon atoms or a
polyvalent cyclic heterocarbon fragment of 1 to about 27 carbon
atoms that was obtained by substitution of hydrogen atoms equal to
the sum of c+e;
each occurrence of X.sup.1 is independently selected from --Cl,
--Br, --OH, --OR.sup.6, and R.sup.6C(.dbd.O)O--, wherein R.sup.6 is
a monovalent hydrocarbon group having from 1 to 20 carbon
atoms;
each occurrence of X.sup.2 and X.sup.3 is independently selected
from hydrogen, R.sup.6, wherein R.sup.6 is a monovalent hydrocarbon
group having from 1 to 20 carbon atoms, X.sup.1, wherein X.sup.1 is
independently selected from --Cl, --Br, --OH, --OR.sup.6, and
R.sup.6C(.dbd.O)O--, wherein R.sup.6 is a monovalent hydrocarbon
group having from 1 to 20 carbon atoms, and --OSi containing groups
that result from the condensation of silanols; and
each occurrence of the subscripts, a, b, c, d, e, m, n, o, p, and
x, is independently given wherein a, c and e are 1 to about 3; b is
1 to about 5; d is 1 to about 5; m and p are 1 to about 100; n is 1
to about 15; o is 0 to about 10; and x is 1 to about 10;
(b) at least one vulcanizable rubber selected from natural rubbers,
synthetic polyisoprene rubbers, polyisobutylene rubbers,
polybutadiene rubbers, and random styrene-butadiene rubbers (SBR);
and
(c) an active filler including at least one of active filler
selected from carbon blacks, silicas, silicon based fillers, and
metal oxides present in a combined amount of at least 35 parts by
weight per 100 parts by weight of total vulcanizable rubber, of
which at least 10 parts by weight is carbon black, silica, or a
combination thereof; and
wherein the tire composition is formulated to be vulcanizable to
form a tire component compound having a Shore A Hardness of not
less than 40 and not greater than 95 and a glass-transition
temperature Tg (E''.sub.max) not less than -80.degree. C. and not
greater than 0.degree. C.
The present invention is also directed to tires at least one
component of which comprises cured tire compositions obtained from
rubber compositions according to the present invention.
The present invention is also directed to tire components, cured
and uncured, including, but not limited to, tire treads, including
any tire component produced from any composition including at least
a silated core polysulfide.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is further described in the detailed
description that follows by way of non-limiting examples of
exemplary embodiments of the present invention, wherein:
FIG. 1 shows HPLC analysis of the product of Example 1.
DETAILED DESCRIPTIONS OF THE PRESENT INVENTION
The silated cyclic core polysulfides of the present invention are
represented by Formula (1)
[Y.sup.1R.sup.1S.sub.x--].sub.m[G.sup.1(SR.sup.2SiX.sup.1X.sup.2X.sup.3).-
sub.a].sub.n[G.sup.2].sub.o[R.sup.3Y.sup.2].sub.p (1) wherein each
occurrence of G.sup.1 is independently selected from polyvalent
cyclic hydrocarbon or heterocarbon species having from 1 to about
30 carbon atoms and containing a polysulfide group represented by
Formula (2)
[(CH.sub.2).sub.b--].sub.cR.sup.4[--(CH.sub.2).sub.dS.sub.x--].sub.e;
(2)
each occurrence of G.sup.2 is independently selected from
polyvalent cyclic hydrocarbon or heterocarbon species of 1 to about
30 carbon atoms and containing a polysulfide group represented by
Formula (3)
[(CH.sub.2).sub.b--].sub.cR.sup.5[--(CH.sub.2).sub.dS.sub.x--].sub.e;
(3)
each occurrence of R.sup.1 and R.sup.3 are independently selected
from a divalent hydrocarbon fragment having from 1 to about 20
carbon atoms that include branched and straight chain alkyl
alkenyl, alkynyl, aryl or aralkyl groups in which one hydrogen atom
was substituted with a Y.sup.1 or Y.sup.2 group; each occurrence of
Y.sup.1 and Y.sup.2 is independently selected from, but not limited
to silyl (--SiX.sup.1X.sup.2X.sup.3), alkoxy (--OR.sup.6),
hydrogen, carboxylic acid (--C(--O)OH), ester (--C(.dbd.O)OR.sup.6,
wherein R.sup.6 is a monovalent hydrocarbon group having from 1 to
20 carbon atoms, and includes branched or straight chain alkyl
alkenyl, aryl or aralkyl groups, and the like;
each occurrence of R.sup.2 is independently selected from a
divalent hydrocarbon fragment having from 1 to about 20 carbon
atoms that include branched and straight chain alkyl, alkenyl,
alkynyl, aryl or aralkyl groups;
each occurrence of R.sup.4 is independently selected from a
polyvalent cyclic hydrocarbon fragment of 1 to about 28 carbon
atoms that was obtained by substitution of hydrogen atoms equal to
the sum of a+c+e, and include cyclic and polycyclic alkyl, alkenyl,
alkynyl, aryl and aralkyl groups in which a+c+e-1 hydrogens have
been replaced, or a polyvalent cyclic heterocarbon fragment from 1
to 27 carbon atoms that was obtained by substitution of hydrogen
atoms equal to the sum of a+c+e;
each occurrence of R.sup.5 is independently selected from a
polyvalent cyclic hydrocarbon fragment of 1 to about 28 carbon
atoms that was obtained by substitution of hydrogen atoms equal to
the sum of c+e and include cyclic and polycyclic alkyl, alkenyl,
alkynyl, aryl and aralkyl groups in which c+e-1 hydrogens have been
replaced, or a polyvalent cyclic heterocarbon fragment from 1 to 27
carbon atoms that was obtained by substitution of hydrogen atoms
equal to the sum of c+e;
each occurrence of X.sup.1 is independently selected from
hydrolysable groups selected from --Cl, --Br, --OH, --OR.sup.6, and
R.sup.6C(.dbd.O)O--, wherein R.sup.6 is any monovalent hydrocarbon
group having from 1 to 20 carbon atoms, and includes branched or
straight chain alkyl, alkenyl, aryl or aralkyl groups;
each occurrence of X.sup.2 and X.sup.3 is independently selected
from hydrogen, any of R.sup.6 as listed above, any of X.sup.1 as
listed above and --OSi containing groups that result from the
condensation of silanols; and
each occurrence of the subscripts, a, b, c, d, e, m, n, o, p, and
x, is independently given by a is 1 to about 3; b is 1 to about 5;
c is 1 to about 3; d is 1 to about 5; e is 1 to about 3; m is 1 to
about 100, n is 1 to about 15; o is 0 to about 10; p is 1 to about
100, and x is 1 to about 10.
The term, "heterocarbon", as used herein, refers to any hydrocarbon
structure in which the carbon-carbon bonding backbone is
interrupted by bonding to hetero atoms, such as atoms of nitrogen,
sulfur, phosphorus and/or oxygen, or in which the carbon-carbon
bonding backbone is interrupted by bonding to groups of atoms
containing sulfur, nitrogen and/or oxygen, such as cyanurate
(C.sub.3N.sub.3). Heterocarbon fragments also refer to any
hydrocarbon in which a hydrogen or two or more hydrogens bonded to
carbon are replaced with a sulfur, oxygen or nitrogen atom, such as
a primary amine (--NH.sub.2), and oxo (.dbd.O), and the like.
Thus, R.sup.4 and R.sup.5 include, but is not limited to cyclic,
and/or polycyclic polyvalent aliphatic hydrocarbons that may be
substituted with alkyl, alkenyl, alkynyl, aryl and/or aralkyl
groups; cyclic and/or polycyclic polyvalent heterocarbon optionally
containing ether functionality via oxygen atoms each of which is
bound to two separate carbon atoms, polysulfide functionality, in
which the polysulfide group (--S.sub.x--) is bonded to two separate
carbon atoms on G.sup.1 or G.sup.2 to form a ring, tertiary amine
functionality via nitrogen atoms each of which is bound to three
separate carbon atoms, cyano (CN) groups, and/or cyanurate
(C.sub.3N.sub.3) groups; aromatic hydrocarbons; and arenes derived
by substitution of the aforementioned aromatics with branched or
straight chain alkyl, alkenyl, alkynyl, aryl and/or aralkyl
groups.
As used herein, "alkyl" includes straight, branched and cyclic
alkyl groups; "alkenyl" includes any straight, branched, or cyclic
alkenyl group containing one or more carbon-carbon double bonds,
where the point of substitution can be either at a carbon-carbon
double bond or elsewhere in the group; and "alkynyl" includes any
straight, branched, or cyclic alkynyl group containing one or more
carbon-carbon triple bonds and optionally also one or more
carbon-carbon double bonds as well, where the point of substitution
can be either at a carbon-carbon triple bond, a carbon-carbon
double bond, or elsewhere in the group. Examples of alkyls include,
but are not limited to, methyl, ethyl, propyl, isobutyl. Examples
of alkenyls include vinyl, but are not limited to, propenyl, allyl,
methallyl, ethylidenyl norbornane, ethylidene norbornyl,
ethylidenyl norbornene, and ethylidene norbornenyl. Some examples
of alkynyls include, but are not limited to, acetylenyl, propargyl,
and methylacetylenyl.
As used herein, "aryl" includes any aromatic hydrocarbon from which
one hydrogen atom has been removed; "aralkyl" includes any of the
aforementioned alkyl groups in which one or more hydrogen atoms
have been substituted by the same number of like and/or different
aryl (as defined herein) substituents; and "arenyl" includes any of
the aforementioned aryl groups in which one or more hydrogen atoms
have been substituted by the same number of like and/or different
alkyl (as defined herein) substituents. Some examples of aryls
include, but are not limited to, phenyl and naphthalenyl. Examples
of aralkyls include, but are not limited to, benzyl and phenethyl,
and some examples of arenyls include tolyl and xylyl.
As used herein, "cyclic alkyl", "cyclic alkenyl", and "cyclic
alkynyl" also include bicyclic, tricyclic, and higher cyclic
structures, as well as the aforementioned cyclic structures further
substituted with alkyl, alkenyl, and/or alkynyl groups.
Representative examples include, but are not limited to, norbornyl,
norbornenyl, ethylnorbornyl, ethylnorbornenyl, cyclohexyl,
ethylcyclohexyl, ethylcyclohexenyl, cyclohexylcyclohexyl, and
cyclododecatrienyl, and the like.
Representative examples of X.sup.1 include, but are not limited to,
methoxy, ethoxy, propoxy, isopropoxy, butoxy, phenoxy, benzyloxy,
hydroxy, chloro, and acetoxy. Representative examples of X.sup.2
and X.sup.3 include the representative examples listed above for
X.sup.1 as well as hydrogen, methyl, ethyl, propyl, isopropyl,
sec-butyl, phenyl, vinyl, cyclohexyl, and higher straight-chain
alkyl, such as butyl, hexyl, octyl, lauryl, and octadecyl, and the
like.
Representative examples of R.sup.1, R.sup.2 and R.sup.3 include the
terminal straight-chain alkyls further substituted terminally at
the other end, such as --CH.sub.2--, --CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2CH.sub.2--, and
--CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2CH.sub.2--,
and their beta-substituted analogs, such as
--CH.sub.2(CH.sub.2).sub.uCH(CH.sub.3)--, where u is zero to 17;
the structure derivable from methallyl chloride,
--CH.sub.2CH(CH.sub.3)CH.sub.2--; any of the structures derivable
from divinylbenzene, such as
--CH.sub.2CH.sub.2(C.sub.6H.sub.4)CH.sub.2CH.sub.2-- and
--CH.sub.2CH.sub.2(C.sub.6H.sub.4)CH(CH.sub.3)--, where the
notation C.sub.6H.sub.4 denotes a disubstituted benzene ring; any
of the structures derivable from diallylether, such as
--CH.sub.2CH.sub.2CH.sub.2OCH.sub.2CH.sub.2CH.sub.2-- and
--CH.sub.2CH.sub.2CH.sub.2OCH.sub.2CH(CH.sub.3)--; any of the
structures derivable from butadiene, such as
--CH.sub.2CH.sub.2CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2CH(CH.sub.3)--, and
--CH.sub.2CH(CH.sub.2CH.sub.3)--; any of the structures derivable
from piperylene, such as --CH.sub.2CH.sub.2CH.sub.2CH(CH.sub.3)--,
--CH.sub.2CH.sub.2CH(CH.sub.2CH.sub.3)--, and
--CH.sub.2CH(CH.sub.2CH.sub.2CH.sub.3)--; any of the structures
derivable from isoprene, such as
--CH.sub.2CH(CH.sub.3)CH.sub.2CH.sub.2--,
--CH.sub.2CH(CH.sub.3)CH(CH.sub.3)---CH.sub.2C(CH.sub.3)(CH.sub.2CH.sub.3-
)--, --CH.sub.2CH.sub.2CH(CH.sub.3)CH.sub.2--,
--CH.sub.2CH.sub.2C(CH.sub.3).sub.2-- and
--CH.sub.2CH[CH(CH.sub.3).sub.2]--; any of the isomers of
--CH.sub.2CH.sub.2-norbornyl-, --CH.sub.2CH.sub.2-cyclohexyl-; any
of the diradicals obtainable from norbornane, cyclohexane,
cyclopentane, tetrahydrodicyclopentadiene, or cyclododecene by loss
of two hydrogen atoms; the structures derivable from limonene,
--CH.sub.2CH(4-methyl-1-C.sub.6H.sub.9--)CH.sub.3, where the
notation C.sub.6H.sub.9 denotes isomers of the trisubstituted
cyclohexane ring lacking substitution in the 2 position; any of the
monovinyl-containing structures derivable from trivinylcyclohexane,
such as --CH.sub.2CH.sub.2(vinylC.sub.6H.sub.9)CH.sub.2CH.sub.2--
and --CH.sub.2CH.sub.2(vinylC.sub.6H.sub.9)CH(CH.sub.3)--, where
the notation C.sub.6H.sub.9 denotes any isomer of the
trisubstituted cyclohexane ring; any of the monounsaturated
structures derivable from myrcene containing a trisubstituted
C.dbd.C, such as
--CH.sub.2CH[CH.sub.2CH.sub.2CH.dbd.C(CH.sub.3).sub.2]CH.sub.2CH.sub.2--,
--CH.sub.2CH[CH.sub.2CH.sub.2CH--C(CH.sub.3).sub.2]CH(CH.sub.3)--,
--CH.sub.2C[CH.sub.2CH.sub.2CH.dbd.C(CH.sub.3).sub.2](CH.sub.2CH.sub.3)---
,
--CH.sub.2CH.sub.2CH[CH.sub.2CH.sub.2CH.dbd.C(CH.sub.3).sub.2]CH.sub.2---
,
--CH.sub.2CH.sub.2(C--)(CH.sub.3)[CH.sub.2CH.sub.2CH.dbd.C(CH.sub.3).sub-
.2], and
--CH.sub.2CH[CH(CH.sub.3)[CH.sub.2CH.sub.2CH.dbd.C(CH.sub.3).sub.-
2]]--; and any of the monounsaturated structures derivable from
myrcene lacking a trisubstituted C.dbd.C, such as
--CH.sub.2CH(CH.dbd.CH.sub.2)CH.sub.2CH.sub.2CH.sub.2C(CH.sub.3).sub.2--,
--CH.sub.2CH(CH.dbd.CH.sub.2)CH.sub.2CH.sub.2CH[CH(CH.sub.3).sub.2]--,
--CH.sub.2C(.dbd.CH--CH.sub.3)CH.sub.2CH.sub.2CH.sub.2C(CH.sub.3).sub.2---
,
--CH.sub.2C(.dbd.CH--CH.sub.3)CH.sub.2CH.sub.2CH[CH(CH.sub.3).sub.2]--,
--CH.sub.2CH.sub.2C(.dbd.CH.sub.2)CH.sub.2CH.sub.2CH.sub.2C(CH.sub.3).sub-
.2--,
--CH.sub.2CH.sub.2C(.dbd.CH.sub.2)CH.sub.2CH.sub.2CH[CH(CH.sub.3).su-
b.2]--,
--CH.sub.2CH.dbd.C(CH.sub.3).sub.2CH.sub.2CH.sub.2CH.sub.2C(CH.sub-
.3).sub.2--, and
--CH.sub.2CH.dbd.C(CH.sub.3).sub.2CH.sub.2CH.sub.2CH[CH(CH.sub.3).sub.2].
Representative examples of G.sup.1 include, but are not limited to,
structures derivable from divinylbenzene, such as
--CH.sub.2CH.sub.2(C.sub.6H.sub.4)CH(CH.sub.2--)--,
--CH.sub.2CH.sub.2(C.sub.6H.sub.3--)CH.sub.2CH.sub.2--,
--CH.sub.2(CH--)(C.sub.6H.sub.4)CH(CH.sub.2--)--, where the
notation C.sub.6H.sub.4 denotes a disubstituted benzene ring and
C.sub.6H.sub.3-- denotes a trisubstituted ring; any structures
derivable from trivinylcyclohexane, such as
--CH.sub.2(CH--)(vinylC.sub.6H.sub.9)CH.sub.2CH.sub.2--,
(--CH.sub.2CH.sub.2).sub.3C.sub.6H.sub.9,
(--CH.sub.2CH.sub.2).sub.2C.sub.6H.sub.9CH(CH.sub.3)--,
--CH.sub.2(CH--)(vinylC.sub.6H.sub.9)(CH--)CH.sub.2--,
--CH.sub.2CH.sub.2C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.2,
--CH(CH.sub.3)C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.2, and
C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.3,
--CH.sub.2(CH--)C.sub.6H.sub.9[CH.sub.2CH.sub.2--].sub.2, and
--CH.sub.2(CH--)C.sub.6H.sub.9[CH(CH.sub.3)--][CH.sub.2CH.sub.2--],
where the notation C.sub.6H.sub.9 denotes any isomer of the
trisubstituted cyclohexane ring.
Representative examples of G.sup.2 include, but are not limited to,
structures derivable from divinylbenzene, such as
--CH.sub.2CH.sub.2(C.sub.6H.sub.4)CH.sub.2CH.sub.2--,
--CH.sub.2CH.sub.2(C.sub.6H.sub.4)CH(CH.sub.2--)--,
CH.sub.2CH.sub.2(C.sub.6H.sub.3--)CH.sub.2CH.sub.2--,
--CH.sub.12(CH--)(C.sub.6H.sub.4)CH(CH.sub.2--)--, where the
notation C.sub.6H.sub.4 denotes a disubstituted benzene ring and
C.sub.6H.sub.3-- denotes a trisubstituted ring; any structures
derivable from trivinylcyclohexane, such as
--CH.sub.2CH.sub.2(vinylC.sub.6H.sub.9)CH.sub.2CH.sub.2--,
(--CH.sub.2CH.sub.2)C.sub.6H.sub.91CH.sub.2CH.sub.3,
--CH.sub.2(CH--)(vinylC.sub.6H.sub.9)CH.sub.2CH.sub.2--,
(--CH.sub.2CH.sub.2).sub.3C.sub.6H.sub.9,
(--CH.sub.2CH.sub.2).sub.2C.sub.6H.sub.9CH(CH.sub.3)--,
--CH.sub.2(CH--)(vinylC.sub.6H.sub.9)(CH--)CH.sub.2--,
--CH.sub.2CH.sub.2C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.2,
--CH(CH.sub.3)C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.2,
C.sub.6H.sub.9[(CH--)CH.sub.2--].sub.3,
--CH.sub.2(CH--)C.sub.6H.sub.9[CH.sub.2CH.sub.2--].sub.2,
--CH.sub.2(CH--)C.sub.6H.sub.9[CH(CH.sub.3)--][CH.sub.2CH.sub.2--],
where the notation C.sub.6H.sub.9 denotes any isomer of the
trisubstituted cyclohexane ring.
Representative examples of silated cyclic core polysulfide silanes
of the present invention include, but are not limited to, any of
the isomers of
4-(6-triethoxysilyl-3-thiahexyl)-1,2-bis-(13-triethoxysilyl-3,4,5,6-tetra-
thiatridecyl)cyclohexane;
4-(6-triethoxysilyl-3-thiahexyl)-1,2-bis-(13-triethoxysilyl-3,4-dithiatri-
decyl)cyclohexane;
4-(6-triethoxysilyl-3-thiahexyl)-1,2-bis-(13-triethoxysilyl-3,4,5-trithia-
tridecyl)cyclohexane;
4-(6-triethoxysilyl-3-thiahexyl)-1,2-bis-(12-triethoxysilyl-3,4,5-tetrath-
iadodecyl)cyclohexane;
1-(6-triethoxysilyl-3-thiahexyl)-2,4-bis-(11-triethoxysilyl-3,4-tetrathia-
unidecyl)cyclohexane
4-(3-triethoxysilyl-1-thiaethyl)-1,2-bis-(13-triethoxysilyl-3,4,5,6,7-pen-
tathiatridecyl)cyclohexane;
4-(6-diethoxymethylsilyl-2-thiahexyl)-1,2-bis-(13-triethoxysilyl-3,4,5,6--
tetrathiatridecyl)cyclohexane;
4-(4-triethoxysilyl-2-thiabutyl)-1,2-bis-(9-triethoxysilyl-3,4,5,6-tetrat-
hianonyl)cyclohexane;
4-(7-triethoxysilyl-3-thiaheptyl)-1,2-bis-(9-triethoxysilyl-3,4,5-trithia-
nonyl)cyclohexane;
4-(5-triethoxysilyl-2-thiapentyl)-1,2-bis-(9-triethoxysilyl-3,4,5,6-tetra-
thianonyl)benzene;
4-(5-triethoxysilyl-2-thiapentyl)-1,2-bis-(9-triethoxysilyl-3,4,5-trithia-
nonyl)benzene;
4-(5-triethoxysilyl-2-thiapentyl)-1,2-bis-(9-triethoxysilyl-3,4-dithianon-
yl)benzene;
bis-2-[4-(3-triethoxysilyl-2-thiapropyl)-3-(9-triethoxysilyl-3,4,5,6-tetr-
athianonyl)cyclohexyl]ethyl tetrasulfide;
bis-2-[4-(3-triethoxysilyl-1-thiapropyl)-3-(9-triethoxysilyl-3,4,5,6-tetr-
athianonyl)cyclohexyl]ethyl trisulfide;
bis-2-[4-(3-triethoxysilyl-1-thiapropyl)-3-(7-triethoxysilyl-3,4-dithiahe-
ptyl)cyclohexyl]ethyl disulfide;
bis-2-[4-(6-triethoxysilyl-3-thiahexyl)-3-(9-triethoxysilyl-3,4,5-trithia-
nonyl)phenyl]ethyl tetrasulfide;
bis-2-[4-(6-triethoxysilyl-3-thiahexyl)-3-(9-triethoxysilyl-3,4,5-trithia-
nonyl)nathyl]ethyl tetrasulfide;
bis-2-[4-(4-diethoxymethylsilyl-2-thiabutyl)-3-(9-triethoxysilyl-3,4,5,6--
tetrathianonyl)phenyl]ethyl trisulfide;
bis-2-[4-(4-triethoxysilyl-2-thiaethyl)-3-(7-triethoxysilyl-3,4-dithiahep-
tyl)cycloheptyl]ethyl disulfide;
bis-2-[4-(4-triethoxysilyl-2-thiaethyl)-3-(7-triethoxysilyl-3,4-dithiahep-
tyl)cyclooctyl]ethyl disulfide;
bis-2-[4-(4-triethoxysilyl-2-thiaethyl)-3-(7-triethoxysilyl-3,4-dithiahep-
tyl)cyclododecyl]ethyl disulfide; 4-(6-triethoxysilyl-3-thiahexyl)
-1,2-bis-(9-triethoxysilyl-3,4,5,6-tetrathianonyl)cyclohexane;
2-(6-triethoxysilyl-3-thiahexyl)-1,4-bis-(9-triethoxysilyl-3,4,5,6-tetrat-
hianonyl)cyclohexane;
1-(6-triethoxysilyl-3-thiahexyl)-2,4-bis-(9-triethoxysilyl-3,4,5,6-tetrat-
hianonyl)cyclohexane;
4-(6-triethoxysilyl-3-thiahexyl)-1,2-bis-(7-triethoxysilyl-3,4-dithiahept-
yl)cyclohexane;
2-(6-triethoxysilyl-3-thiahexyl)-1,4-bis-(7-triethoxysilyl-3,4-dithiahept-
yl)cyclohexane;
1-(6-triethoxysilyl-3-thiahexyl)-2,4-bis-(7-triethoxysilyl-3,4-dithiahept-
yl)cyclohexane; and mixture thereof.
In another embodiment of the present invention, the Formulae (1),
(2) and (3), are described wherein each occurrence of R.sup.1 and
R.sup.3 are independently selected from a divalent hydrocarbon
fragment having from 1 to about 5 carbon atoms that include
branched and straight chain alkyl, alkenyl, alkynyl, aryl or
aralkyl groups in which one hydrogen atom was substituted with a
Y.sup.1 or Y.sup.2 group; each occurrence of Y.sup.1 and Y.sup.2 is
chosen independently from silyl (--SiX.sup.1X.sup.2X.sup.3); each
occurrence of R.sup.2 is a straight chain hydrocarbon represented
by --(CH.sub.2).sub.f-- where f is an integer from about 1 to about
5; each occurrence of R.sup.4 is chosen independently from a
polyvalent cyclic hydrocarbon fragment of 5 to about 12 carbon
atoms that was obtained by substitution of hydrogen atoms equal to
the sum of a+c+e, and include cyclic alkyl, aryl and arenyl in
which a+c+e-1 hydrogens have been replaced; each occurrence of
R.sup.5 is chosen independently from a polyvalent cyclic
hydrocarbon fragment of 5 to about 12 carbon atoms that was
obtained by substitution of hydrogen atoms equal to the sum of a+c,
and include cyclic alkyl, aryl and arenyl in which a+c-1 hydrogens
have been replaced; each occurrence of X.sup.1 is chosen
independently from the set of hydrolysable groups selected from
--OH, --OR.sup.6, in which R.sup.6 is a monovalent hydrocarbon
group having from 1 to 5 carbon atoms, and includes branched or
straight chain alkyl, alkenyl, aryl or aralkyl groups; each
occurrence of X.sup.2 and X.sup.3 is independently taken from
R.sup.6 as defined for this embodiment, any of X.sup.1 as defined
for this embodiment and --OSi containing groups that result from
the condensation of silanols; each occurrence of the subscripts, a,
b, c, d, e, f, m, n, o, p, and x, is independently given by a is 1
to about 2; b is 1 to about 3; c is 1; d is 1 to about 3; e is 1; f
is 0 to about 5; m is 1, n is 1 to about 10; o is 0 to about 1; p
is 1, and x is 1 to about 6.
In another embodiment, 30 to 99 weight percent of the silated
cyclic core polysulfide of the present invention is blended with 70
to 1 weight percent of another silane, including silanes of the
structure represented in Formula (4)
[X.sup.1X.sup.2X.sup.3SiR.sup.1S.sub.xR.sup.3SiX.sup.1X.sup.2X.sup.3]
(4) wherein each occurrence of R.sup.1 and R.sup.3 are chosen
independently from a divalent hydrocarbon fragment having from 1 to
about 20 carbon atoms that include branched and straight chain
alkyl, alkenyl, alkynyl, aryl or aralkyl groups in which one
hydrogen atom was substituted with independently a
--SiX.sup.1X.sup.2X.sup.3 group, wherein X.sup.1 is chosen
independently from any of hydrolysable groups selected from --Cl,
--Br, --OH, --OR.sup.6, and R.sup.6C(.dbd.O)O--, in which R.sup.6
is any monovalent hydrocarbon group having from 1 to 20 carbon
atoms, and includes branched or straight chain alkyl, alkenyl, aryl
or aralkyl group, and X.sup.2 and X.sup.3 are independently taken
from hydrogen, R.sup.6 as defined above, any of X.sup.1 as defined
above, and --OSi containing groups that result from the
condensation of silanols.
Representative examples of the silane described by Formula 4 are
listed in U.S. Pat. No. 3,842,111, which is incorporated by
reference herein in its entirety, and include
bis-(3-triethoxysilylpropyl) disulfide;
bis-(3-triethoxysilylpropyl) trisulfide;
bis-(3-triethoxysilylpropyl) tetrasulfide,
bis-(3-triethoxysilylpropyl) pentasulfide;
bis-(3-diethoxymethylsilylpropyl) disulfide;
bis-(3-ethoxydimethylsilylpropyl) disulfide;
bis-(triethoxysilylmethyl) disulfide; bis-(4-triethoxysilylbenzyl)
disulfide; bis-(3-triethoxysilylphenyl) disulfide and the like.
The bonding of sulfur to a methylene group on R.sup.4 and R.sup.5
is desired because the methylene group mitigates excessive steric
interactions between the silane and the filler and polymer. Two
successive methylene groups mitigate steric interactions even
further and also add flexibility to the chemical structure of the
silane, thereby enhancing its ability to accommodate the positional
and orientational constraints imposed by the morphologies of the
surfaces of both the rubber and filler at the interphase, at the
molecular level. The silane flexibility becomes increasingly
important as the total number of silicon and sulfur atoms bound to
G.sup.1 and G.sup.2 increases from 3 to 4 and beyond. Structures in
which the polysulfide group is bonded directly to secondary and
tertiary carbon atoms, ring structures, especially aromatic
structures, are rigid and sterically hindered. The accelerators and
curatives cannot readily orient themselves with the polysulfide
group to affect reaction and the silated cyclic core polysulfide
cannot readily orient itself to meet available binding sites on
silica and polymer. This would tend to leave sulfur groups unbound
to polymer, thereby reducing the efficiency by which the principle
of multiple bonding of silane to polymer via multiple sulfur groups
on silane, is realized.
The use of a sulfide group to attach the silyl group to the core,
--S--R.sup.2SiX.sup.1X.sup.2X.sup.3 provides a convenient and cost
effective way to bond the silyl group to the core. The sulfide
group is less reactive than the polysulfide groups of the present
invention and therefore is less likely to be broken during the
curing of the rubbers containing the silated cyclic core
polysulfides. The sulfide linkage of the silyl group to the core
also makes it easier to synthesize molecules with different lengths
of the R.sup.2 relative to R.sup.1 and R.sup.3 and therefore to
optimize the chemical structure of the silated cyclic core
polysulfides to achieve bonding between the inorganic filler, such
as silica, and the rubber.
The function of the other silanes in the blend are to occupy sites
on the surface of the silica which aid in dispersing the silica and
coupling with the polymer.
Process for Preparing Silated Cyclic Core Polysulfides
In another embodiment of the present invention, the silated cyclic
core polysulfides are prepared by (a) reacting a thioacid with the
structure, R.sup.6C(.dbd.O)SH, with a hydrocarbon containing
reactive double bonds; (b) deblocking the mercapto group using a
proton donator; (c) reacting the intermediate mercaptan in (b) with
a base and then a halo containing hydrocarbon silane; (d) reacting
the intermediate mercapto silane from (c) with a base and sulfur;
(e) reacting the intermediate in (d) with a substituted or
unsubstituted hydrocarbon containing a leaving group selected from
chlorine, bromine or iodine.
The structure of the hydrocarbon containing reactive double bonds
in (a) can be represented by the chemical structure shown of
Formula (5)
##STR00001## wherein each occurrence is described supra and the
subscripts g, h and i are independently given by g is about 0 to 3;
h is 0 to about 3; and i is 0 to about 3.
The free radical reagent includes oxidizing agents that are capable
of converting the thiocarboxylic acid to a thiocarboxylic acid
radical, i.e. R.sup.6C(.dbd.O)S.cndot., and include, but are not
limited to oxygen, peroxides, hydroperoxides, and the like.
The proton donor species are any hydrogen containing heterocarbon
or substituted heterocarbon that is capable of reacting with the
thiocarboxylic acid ester intermediate in (c) to generate an
unblocked mercaptan. Representative examples of these hydrogen
donor species include alcohols, such as methanol, ethanol,
isopropyl alcohol, propanol, and the like; amines such as ammonia,
methyl amine, propyl amine, diethanol amine, and the like;
mercaptans, such as propyl mercaptans, butyl mercaptan, and the
like.
The structure of the substituted or unsubstituted hydrocarbon
containing a leaving group used in (e) is represented by Formulae
(6) and (7) Y.sup.1R.sup.1Z (Formula 6) Y.sup.2R.sup.3Z (Formula 7)
wherein each occurrence of Y.sup.1, Y.sup.2, R.sup.1, and R.sup.3
are as previously defined and Z is selected from the group Cl, Br
and I.
The structure of the halo containing hydrocarbon silane used in (c)
is represented by Formula (8) ZR.sup.2SiX.sup.1X.sup.2X.sup.3 (8)
wherein each occurrence of R.sup.2, X.sup.1, X.sup.2 and X.sup.3
are as previously defined and Z is selected from the group Cl, Br
and I.
The reactions may be carried out in the presence or absence of
organic solvents, including alcohols, ethers, hydrocarbon solvents,
and the like. Representative examples of suitable organic solvents
include, but are not limited to, ethanol, methanol, isopropyl
alcohol, tetrahydrofuran, diethyl ether, hexanes, cyclohexane,
toluene, xylenes, and mixtures thereof, and the like.
Use in Rubber Compositions
In one embodiment of the present invention, there is provided a
rubber composition comprising: (a) the silated cyclic core
polysulfide of the present invention (Formula 1); (b) inorganic
filler; and, (c) rubber.
In another embodiment of the present invention, there is provided a
cured rubber composition comprising: (a) the silated cyclic core
polysulfide of the present invention (Formula 1); (b) inorganic
filler; (c) rubber; (d) curatives; and, (e) optionally, other
additives.
The rubbers useful with the coupling agents described herein
include sulfur vulcanizable rubbers including conjugated diene
homopolymers and copolymers, and copolymers of at least one
conjugated diene and aromatic vinyl compound. Rubbers useful in the
present invention includes natural or synthetic elastomers,
including polyisoprene rubbers, polyisobutylene rubbers,
polybutadiene rubbers and styrenebutadiene rubbers. Suitable
organic polymers for preparation of rubber compositions are well
known in the art and are described in various textbooks including
The Vanderbilt Rubber Handbook, Ohm, R. F., R. T. Vanderbilt
Company, Inc., 1990 and in the Manual for the Rubber Industry,
Kemperman, T and Koch, S. Jr., Bayer A G, LeverKusen, 1993, the
disclosures of which are incorporated by reference herein in their
entireties.
One example of a suitable polymer for use herein is
solution-prepared styrene-butadiene rubber (sSBR). In one
embodiment of the invention, the solution prepared sSBR has a bound
styrene content in a range of about 5 to about 50 weight percent.
In another embodiment of the invention, the solution prepared sSBR
has a bound styrene content in a range of about 9 to about 36
weight percent. Other useful polymers include emulsion-prepared
styrene-butadiene rubber (eSBR), natural rubber (NR),
ethylene-propylene copolymers and terpolymers (EP, EPDM),
acrylonitrile-butadiene rubber (NBR), polybutadiene (BR), and so
forth.
In another embodiment, the rubber composition is comprised of at
least one diene-based elastomer, or rubber. Suitable conjugated
dienes include, but are not limited to, isoprene and 1,3-butadiene
and suitable vinyl aromatic compounds include, but are not limited
to, styrene and alpha methyl styrene. Polybutadiene may be
characterized as existing primarily, typically about 90% by weight,
in the cis-1,4-butadiene form, but other compositions may also be
used for the purposes described herein.
Thus, the rubber is a sulfur curable rubber. Such diene based
elastomer, or rubber, may be selected, for example, from at least
one of cis-1,4-polyisoprene rubber (natural and/or synthetic),
emulsion polymerization prepared styrene/butadiene copolymer
rubber, organic solution polymerization prepared styrene/butadiene
rubber, 3,4-polyisoprene rubber, isoprene/butadiene rubber,
styrene/isoprene/butadiene terpolymer rubber,
cis-1,4-polybutadiene, medium vinyl polybutadiene rubber (35-50
percent vinyl), high vinyl polybutadiene rubber (50-75 percent
vinyl), styrene/isoprene copolymers, emulsion polymerization
prepared styrene/butadiene/acrylonitrile terpolymer rubber and
butadiene/acrylonitrile copolymer rubber. In one embodiment of the
invention, an emulsion polymerization derived styrene/butadiene
(eSBR) having a relatively conventional styrene content of about 20
to about 28 percent bound styrene is used. In another embodiment,
an eSBR having a medium to relatively high bound styrene content of
about 30 to about 45 percent may be used.
Emulsion polymerization prepared styrene/butadiene/acrylonitrile
terpolymer rubbers containing from about 2 to about 40 weight
percent bound acrylonitrile in the terpolymer are also contemplated
as diene based rubbers for use in this invention.
A particulate filler, particulate composition, includes a particle
or grouping of particles to form aggregates or agglomerates,
including reinforcement filler or particles, including without
limitation, those containing or made from organic molecules,
oligomers, and/or polymers, e.g., poly(arylene ether) resins, or
functionalized reinforcement filler or particle.
The term functionalized is intended to include any particles
treated with an organic molecule, polymer, oligomer, or otherwise
(collectively, treating agent(s)), thereby chemically bonding the
treating agent(s) to the particle. The particulate filler of the
present invention can be essentially inert to the silane with which
it is admixed, or it can be reactive therewith. The particulate
filler which may also be added to the crosslinkable elastomer
compositions of the present invention includes siliceous fillers,
carbon black, and so forth. The filler materials useful herein
include, but are not limited to, metal oxides such as silica
(pyrogenic and/or precipitated), titanium dioxide, aluminosilicate
and alumina, clays and talc, carbon black, and so forth.
Particulate, precipitated silica is also sometimes used for such
purpose, particularly when the silica is used in conjunction with a
silane. In some cases, a combination of silica and carbon black is
utilized for reinforcing fillers for various rubber products,
including treads for tires. Alumina can be used either alone or in
combination with silica. The term, alumina, can be described herein
as aluminum oxide, or Al.sub.2O.sub.3. The fillers may be hydrated
or in anhydrous form.
The silated cyclic core polysulfide silane(s) may be premixed or
pre-reacted with the filler particles, or added to the rubber mix
during the rubber and filler processing, or mixing stages. If the
silated cyclic core polysulfide silanes and filler are added
separately to the rubber mix during the rubber and filler mixing,
or processing stage, it is considered that the silated cyclic core
polysulfide silane(s) then combiners) in an in-situ fashion with
the filler.
The vulcanized rubber composition should contain a sufficient
amount of filler to contribute a reasonably high modulus and high
resistance to tear. In one embodiment of the present invention, the
combined weight of the filler may be as low as about 5 to about 120
parts by weight per hundred parts rubber (phr), or about 5 to about
100 phr. In another embodiment, the combined weight of the filler
is from about 25 to about 85 phr and at least one precipitated
silica is utilized as a filler. The silica may be characterized by
having a BET surface area, as measured using nitrogen gas, in the
range of about 40 to about 600 m.sup.2/g. In another embodiment of
the invention, the silica has a BET surface area in a range of
about 50 to about 300 m.sup.2/g. The BET method of measuring
surface area is described in the Journal of the American Chemical
Society, Volume 60, page 304 (1930), which is incorporated by
reference herein in its entirety. The silica typically may also be
characterized by having a dibutylphthalate (DBP) absorption value
in a range of about 100 to about 350, and more usually about 150 to
about 300. Further, the silica, as well as the aforesaid alumina
and aluminosilicate, may be expected to have a CTAB surface area in
a range of about 100 to about 220. The CTAB surface area is the
external surface area as evaluated by cetyl trimethylammonium
bromide with a pH of about 9. The method is described in ASTM D
3849, which is incorporated by reference in its entirety.
Mercury porosity surface area is the specific surface area
determined by mercury porosimetry. Using this method, mercury is
penetrated into the pores of the sample after a thermal treatment
to remove volatiles. Set up conditions may be suitably described as
using a 100 mg sample; removing volatiles during 2 hours at
105.degree. C. and ambient atmospheric pressure; ambient to 2000
bars pressure measuring range. Such evaluation may be performed
according to the method described in Winslow, Shapiro in ASTM
bulletin, p. 39 (1959) or according to DIN 66133. For such an
evaluation, a CARLO-ERBA Porosimeter 2000 might be used. The
average mercury porosity specific surface area for the silica
should be in a range of 100 to 300 m.sup.2/g.
In one embodiment of the invention, a suitable pore size
distribution for the silica, alumina and aluminosilicate according
to such mercury porosity evaluation is considered herein to be such
that five percent or less of its pores have a diameter of less than
about 10 nm, about 60 to about 90 percent of its pores have a
diameter of about 10 to about 100 nm, about 10 to about 30 percent
of its pores have a diameter at about 100 to about 1,000 nm, and
about 5 to about 20 percent of its pores have a diameter of greater
than about 1,000 nm.
In another embodiment, the silica might be expected to have an
average ultimate particle size, for example, in the range of about
10 to about 50 nm as determined by the electron microscope,
although the silica particles may be even smaller, or possibly
larger, in size. Various commercially available silicas may be
considered for use in this invention such as, from PPG Industries
under the HI-SIL trademark with designations HI-SIL 210, 243, etc.;
silicas available from Rhone-Poulenc, with, for example,
designation of ZEOSIL 1165 MP; silicas available from Degussa with,
for example, designations VN2 and VN3, etc. and silicas
commercially available from Huber having, for example, a
designation of HUBERSIL7 8745.
In still another embodiment, the compositions may utilize fillers
such as silica, alumina and/or aluminosilicates in combination with
carbon black reinforcing pigments. The compositions may comprise a
filler mix of about 15 to about 95 weight percent of the siliceous
filler, and about 5 to about 85 weight percent carbon black,
wherein the carbon black has a CTAB value in a range of 80 to 150.
More typically, it is desirable to use a weight ratio of siliceous
fillers to carbon black of at least about 3/1, and preferably at
least about 10/1. The weight ratio may range from about 3/1 to
about 30/1 for siliceous fillers to carbon black.
In another embodiment, the filler can be comprised of about 60 to
about 95 weight percent of said silica, alumina and/or
aluminosilicate and, correspondingly, about 40 to about 5 weight
percent carbon black. The siliceous filler and carbon black may be
pre-blended or blended together in the manufacture of the
vulcanized rubber.
In yet another embodiment of the present invention, the rubber
compositions of the present invention are prepared by mixing one or
more of the silated cyclic core polysulfide silanes with the
organic polymer before, during or after the compounding of the
filler into the organic polymer. In another embodiment, the silated
cyclic core polysulfide silanes are added before or during the
compounding of the filler into the organic polymer, because these
silanes facilitate and improve the dispersion of the filler. In
another embodiment, the total amount of silated cyclic core
polysulfide silane present in the resulting combination should be
about 0.05 to about 25 parts by weight per hundred parts by weight
of rubber (phr); and 1 to 10 phr in another embodiment. In yet
another embodiment, fillers can be used in quantities ranging from
about 5 to about 120 phr, about 5 to about 100 phr, or about 25 to
about 80 phr, and still in another embodiment from about 25 to
about 110, or about 25 to about 105.
Preferred compositions include those compositions useful for the
manufacture of tires or tire components, including vehicle tires,
and include rubber compositions that include at least one
vulcanizable rubber, a silated core polysulfide, and at least one
active filler such as, by way of nonlimiting example, carbon
blacks, silicas, silicon based fillers, and metal oxides present
either alone or in combinations. For example, an active filler may
be selected from the group described above (e.g., carbon blacks,
silicas, silicon based fillers, and metal oxides) and may be, but
does not have to be, present in a combined amount of at least 35
parts by weight per 100 parts by weight of total vulcanizable
rubber, of which at least 10 parts can be carbon black, silica, or
some combination thereof and wherein said compositions can be
formulated so that they are vulcanizable to form a tire component
compound. The tire component compounds may have a Shore A Hardness
of not less than 40 and not greater than 95 and a glass-transition
temperature Tg (E''.sub.max) not less than -80.degree. C. and not
greater than 0.degree. C. The Shore A Hardness is measured in
accordance with DIN 53505. The glass-transition temperature Tg
(E''.sub.max) is measured in accordance with DIN 53513 with a
specified temperature sweep of -80.degree. C. to +80.degree. C. and
a specified compression of 10.+-.0.2% at 10 Hz. Preferably, the
rubber comprises vulcanizable rubbers selected from natural
rubbers, synthetic polyisoprene rubbers, polyisobutylene rubbers,
polybutadiene rubbers, random styrene-butadiene rubbers (SBR), and
mixtures thereof. Moreover, an active filler includes a filler that
is interactive with the rubber or tire composition and itself, and
changes properties of the rubber or tire composition.
In practice, sulfur vulcanized rubber products typically are
prepared by thermomechanically mixing rubber and various
ingredients in a sequentially step-wise manner followed by shaping
and curing the compounded rubber to form a vulcanized product.
First, for the aforesaid mixing of the rubber and various
ingredients, typically exclusive of sulfur and sulfur vulcanization
accelerators (collectively, curing agents), the rubber(s) and
various rubber compounding ingredients typically are blended in at
least one, and often (in the case of silica filled low rolling
resistance tires) two or more, preparatory thermomechanical mixing
stage(s) in suitable mixers. Such preparatory mixing is referred to
as nonproductive mixing or non-productive mixing steps or stages.
Such preparatory mixing usually is conducted at temperatures of
about 140.degree. C. to 200.degree. C., and for some compositions,
about 150.degree. C. to 180.degree. C. Subsequent to such
preparatory mixing stages, in a final mixing stage, sometimes
referred to as a productive mixing stage, curing agents, and
possibly one or more additional ingredients, are mixed with the
rubber compound or composition, at lower temperatures of typically
about 50.degree. C. to 130.degree. C. in order to prevent or retard
premature curing of the sulfur curable rubber, sometimes referred
to as scorching. The rubber mixture, also referred to as a rubber
compound or composition, typically is allowed to cool, sometimes
after or during a process intermediate mill mixing, between the
aforesaid various mixing steps, for example, to a temperature of
about 50.degree. C. or lower. When it is desired to mold and to
cure the rubber, the rubber is placed into the appropriate mold at
a temperature of at least about 130.degree. C. and up to about
200.degree. C. which will cause the vulcanization of the rubber by
the S--S bond-containing groups (i.e., disulfide, trisulfide,
tetrasulfide, etc.; polysulfide) on the silated cyclic core
polysulfide silanes and any other free sulfur sources in the rubber
mixture.
Thermomechanical mixing refers to the phenomenon whereby under the
high shear conditions in a rubber mixer, the shear forces and
associated friction occurring as a result of mixing the rubber
compound, or some blend of the rubber compound itself and rubber
compounding ingredients in the high shear mixer, the temperature
autogeneously increases, i.e. it "heats up". Several chemical
reactions may occur at various steps in the mixing and curing
processes.
The first reaction is a relatively fast reaction and is considered
herein to take place between the filler and the silicon alkoxide
group of the silated cyclic core polysulfides. Such reaction may
occur at a relatively low temperature such as, for example, at
about 120.degree. C. The second reaction is considered herein to be
the reaction which takes place between the sulfur-containing
portion of the silated cyclic core polysulfide silane, and the
sulfur vulcanizable rubber at a higher temperature; for example,
above about 140.degree. C.
Another sulfur source may be used, for example, in the form of
elemental sulfur, such as but not limited to S.sub.8. A sulfur
donor is considered herein as a sulfur containing compound which
liberates free, or elemental sulfur, at a temperature in a range of
140.degree. C. to 190.degree. C. Such sulfur donors may be, for
example, although are not limited to, polysulfide vulcanization
accelerators and organosilane polysulfides with at least two
connecting sulfur atoms in its polysulfide bridge. The amount of
free sulfur source addition to the mixture can be controlled or
manipulated as a matter of choice relatively independently from the
addition of the aforesaid silated cyclic core polysulfide silane.
Thus, for example, the independent addition of a sulfur source may
be manipulated by the amount of addition thereof and by the
sequence of addition relative to the addition of other ingredients
to the rubber mixture.
In one embodiment of the invention, the rubber composition may
therefore comprise about 100 parts by weight of at least one sulfur
vulcanizable rubber selected from conjugated diene homopolymers and
copolymers, and copolymers of at least one conjugated diene and
aromatic vinyl compound, about 5 to about 100 parts, preferably
about 25 to about 80 parts per hundred parts by weight per 100
parts by weight rubber of at least one particulate filler, up to
about 5 parts by weight per 100 parts by weight rubber of a curing
agent, and about 0.05 to about 25 parts per hundred parts of
polymer of at least one silated cyclic core polysulfide silane as
described in the present invention.
In another embodiment, the filler composition comprises from about
1 to about 85 weight percent carbon black based on the total weight
of the filler composition and up to about 20 parts by weight of at
least one silated core polysulfide silane of the present invention
based on the total weight of the filler composition, including
about 2 to about 20 parts by weight of at least one silated core
polysulfide silane of the present invention based on the total
weight of the filler composition.
In still another embodiment, the rubber composition is prepared by
first blending rubber, filler and silated cyclic core polysulfide
silane, or rubber, filler pretreated with all or a portion of the
silated cyclic core polysulfide silane and any remaining silated
cyclic core polysulfide silane, in a first thermomechanical mixing
step to a temperature of about 140.degree. C. to about 200.degree.
C. for about 2 to about 20 minutes. In another embodiment, filler
pretreated with all or a portion of the silated cyclic core
polysulfide silane and any remaining silated cyclic core
polysulfide silane, in a first thermomechanical mixing step to a
temperature of about 140.degree. C. to about 200.degree. C. for
about 4 to 15 minutes. Optionally, the curing agent is then added
in another thermomechanical mixing step at a temperature of about
50.degree. C. and mixed for about 1 to about 30 minutes. The
temperature is then heated again to between about 130.degree. C.
and about 200.degree. C. and curing is accomplished in about 5 to
about 60 minutes.
In another embodiment, the process may also comprise the additional
steps of preparing an assembly of a tire or sulfur vulcanizable
rubber with a tread comprised of the rubber composition prepared
according to this invention and vulcanizing the assembly at a
temperature in a range of 130.degree. C. to 200.degree. C.
Other optional ingredients may be added in the rubber compositions
of the present invention including curing aids, i.e. sulfur
compounds, including activators, retarders and accelerators,
processing additives such as oils, plasticizers, tackifying resins,
silicas, other fillers, pigments, fatty acids, zinc oxide, waxes,
antioxidants and antiozonants, peptizing agents, reinforcing
materials such as, for example, carbon black, and so forth. Such
additives are selected based upon the intended use and on the
sulfur vulcanizable material selected for use, and such selection
is within the knowledge of one of skill in the art, as are the
required amounts of such additives known to one of skill in the
art.
The vulcanization may be conducted in the presence of additional
sulfur vulcanizing agents. Examples of suitable sulfur vulcanizing
agents include, for example elemental sulfur (free sulfur) or
sulfur donating vulcanizing agents, for example, an amino
disulfide, polymeric polysulfide or sulfur olefin adducts which are
conventionally added in the final, productive, rubber composition
mixing step. The sulfur vulcanizing agents, which can be those
which are common in the art, are used, or added in the productive
mixing stage, in an amount ranging from about 0.4 to about 3 phr,
or even, in some circumstances, up to about 8 phr, with a range of
from about 1.5 to about 2.5 phr and all subranges therebetween in
one embodiment from 2 to about 2.5 phr and all subranges
therebetween in another embodiment.
Optionally, vulcanization accelerators, i.e., additional sulfur
donors, may be used herein. It is appreciated that may include the
following examples, benzothiazole, alkyl thiuram disulfide,
guanidine derivatives and thiocarbamates. Representative of such
accelerators can be, but not limited to, mercapto benzothiazole
(MBT), tetramethyl thiuram disulfide (TMTD), tetramethyl thiuram
monosulfide (TMTM), benzothiazole disulfide (MBTS),
diphenylguanidine (DPG), zinc dithiocarbamate (ZBEC),
alkylphenoldisulfide, zinc iso-propyl xanthate (ZIX),
N-dicyclohexyl-2-benzothiazolesulfenamide (DCBS),
N-cyclohexyl-2-benzothiazolesulfenamide (CBS),
N-tert-butyl-2-benzothiazolesulfenamide (TBBS),
N-tert-butyl-2-benzothiazolesulfenamide (TBSI), tetrabenzylthiuram
disulfide (TBzTD), tetraethylthiuram disulfide (TETD),
N-oxydiethylenebenzothiazole-2-sulfenamide, N,N-diphenylthiourea,
dithiocarbamylsulfenamide,
N,N-diisopropylbenzothiozole-2-sulfenamide,
zinc-2-mercaptotoluimidazole, dithiobis (N-methyl piperazine),
dithiobis (N-beta-hydroxy ethyl piperazine) and dithiobis (dibenzyl
amine). Other additional sulfur donors, may be, for example,
thiuram and morpholine derivatives. Representative of such donors
are, for example, but not limited to, dimorpholine disulfide,
dimorpholine tetrasulfide, tetramethyl thiuram tetrasulfide,
benzothiazyl-2,N-dithiomorpholide, thioplasts,
dipentamethylenethiuram hexasulfide, and disulfidecaprolactam.
Accelerators are used to control the time and/or temperature
required for vulcanization and to improve the properties of the
vulcanizate. In one embodiment, a single accelerator system may be
used, i.e., a primary accelerator. Conventionally, a primary
accelerator(s) is used in total amounts ranging from about 0.5 to
about 4 phr and all subranges therebetween in one embodiment, and
from about 0.8 to about 1.5, phr and all subranges therebetween in
another embodiment. Combinations of a primary and a secondary
accelerator might be used with the secondary accelerator being used
in smaller amounts (of about 0.05 to about 3 phr and all subranges
therebetween) in order to activate and to improve the properties of
the vulcanizate. Delayed action accelerators may be used.
Vulcanization retarders might also be used. Suitable types of
accelerators are amines, disulfides, guanidines, thioureas,
thiazoles, thiurams, sulfenamides, dithiocarbamates and xanthates.
In one embodiment, the primary accelerator is a sulfenamide. If a
second accelerator is used, the secondary accelerator can be a
guanidine, dithiocarbamate and/or thiuram compounds. Preferably,
tetrabenzylthiuram disulfide is utilized as a secondary accelerator
in combination with N-tert-butyl-2-benzothiazolesulfenamide without
or without diphenylguanidine. Tetrabenzylthiuram disulfide is a
preferred accelerator as it does not lead to the production of
nitrosating agents, such as, for example, tetramethylthiuram
disulfide.
Typical amounts of tackifier resins, if used, comprise about 0.5 to
about 10 phr and all subranges therebetween, usually about 1 to
about 5 phr and all subranges therebetween. Typical amounts of
processing aids comprise about 1 to about 50 phr and all subranges
therebetween. Such processing aids can include, for example,
aromatic, napthenic, and/or paraffinic processing oils. Typical
amounts of antioxidants comprise about 1 to about 5 phr.
Representative antioxidants may be, for example,
diphenyl-p-phenylenediamine and others, such as, for example, those
disclosed in the Vanderbilt Rubber Handbook (1978), pages 344-346.
Typical amounts of antiozonants, comprise about 1 to about 5 phr
and all subranges therebetween. Typical amounts of fatty acids, if
used, which can include stearic acid, comprise about 0.5 to about 3
phr and all subranges therebetween. Typical amounts of zinc oxide
comprise about 2 to about 5 phr. Typical amounts of waxes comprise
about 1 to about 5 phr and all subranges therebetween. Often
microcrystalline waxes are used. Typical amounts of peptizers
comprise about 0.1 to about 1 phr and all subranges therebetween.
Typical peptizers may be, for example, pentachlorothiophenol and
dibenzamidodiphenyl disulfide.
The rubber compositions of this invention can be used for various
purposes. For example, it can be used for various tire compounds,
weather stripping, and shoe soles. In one embodiment of the present
invention, the rubber compositions described herein are
particularly useful in tire treads, but may also be used for all
other parts of the tire as well and can comprise various tire
components and various tire component compounds. The tires can be
built, shaped, molded and cured by various methods that are known
and will be readily apparent to those having skill in such art.
The tire compositions are formulated so that they are vulcanizable
to form a tire component compound, the compound having a Shore A
Hardness of not less than 40 and not greater than 95 and a
glass-transition temperature Tg (E''.sub.max) not less than
-80.degree. C. and not greater than 0.degree. C. The Shore A
Hardness according to the present invention is measured in
accordance with DIN 53505. The glass-transition temperature Tg
(E''.sub.max) is measured in accordance with DIN 53513 with a
specified temperature sweep of -80.degree. C. to +80.degree. C. and
a specified compression of 10.+-.0.2% at 10 Hz.".
In another embodiment, the silated cyclic core polysulfide of the
present invention may be loaded on a carrier, or filler, such as,
for example, a porous polymer, carbon black, silica or the like, so
that they are in a dry free flowing form for convenient delivery to
rubber. In one embodiment, the carrier would be part of the
inorganic filler to be used in the rubber.
In one embodiment of the invention, a dry free flowing composition
comprises the silated cyclic core polysulfides in accordance with
this invention in admixture with one or more of the aforesaid
carrier materials, e.g., in a weight ratio of from about 0.1 to
about 60 weight percent. The BET surface area of such carriers as
silica can vary widely and in one embodiment can vary from about
100 m.sup.2/g to about 300 m.sup.2/g. Another property of such
carriers is their DOP adsorption, an oil adsorption index. In the
case of nonporous carriers such as silica, the DOP adsorption can
range from about 100 ml/100 gm to about 400 ml/100 gm. Porous
carriers such as foamed polyolefins can advantageously absorb from
about 10 ml to about 250 ml/100 gm (from about 9 to about 70 weight
percent) of the silane of the present invention.
The filler can be essentially inert to the silane with which it is
admixed as is the case with carbon black or organic polymers, or it
can be reactive therewith, e.g., the case with carriers possessing
metal hydroxyl surface functionality, e.g., silicas and other
silaceous particulates which possess surface silanol
functionality.
All references cited are specifically incorporated herein by
reference as they are relevant to the present invention.
EXAMPLES
The examples presented below demonstrate significant advantages of
the silanes described herein relative to those of the currently
practiced art, in their performance as coupling agents in
silica-filled rubber.
Example 1
Preparation of
(6-triethoxysilyl-3-thia-1-hexyl)-bis-(7-triethoxysilyl-3,4-dithiaheptyl)-
cyclohexane, related oligomers and
bis-(3-triethoxysilylpropyl)polysulfide mixture.
This example illustrates the preparation of a silated cyclic core
disulfide from a core containing three vinyl groups through the
formation of an intermediate thioacetate silane. The
tris-(4-oxo-3-thiapentyl)cyclohexane was prepared by the reaction
of thioacetic acid with trivinylcyclohexane. Into a 5 L, three-neck
round bottomed flask equipped with magnetic stir bar, temperature
probe/controller, heating mantle, addition funnel, condenser, and
air inlet were charged 1,2,4-trivinylcyclohexane (779 grams, 4.8
moles) and t-butyl peroxide (8.0 grams, 0.055 mole). Freshly
distilled thioacetic acid (1297 grams, 16.8 moles) was added by
means of an addition funnel over a period of 30 minutes. The
temperature rose from room temperature to 59.degree. C. The
reaction mixture was allowed to cool to room temperature,
tert-butyl peroxide (25.3 grams, 0.173 moles) was added in two
increments and the reaction mixture was heated overnight at
75.degree. C. After cooling to 42.degree. C., air was bubbled into
the reaction mixture and an exotherm was observed. The mixture was
stirred overnight at 75.degree. C. and ten cooled to room
temperature. The reaction mixture was stripped to remove any low
boiling species under reduced pressure and a maximum temperature of
135.degree. C. to give the final product (1,866 grams, 4.77 moles).
The yield was 99 percent.
The 1,2,4-tris-(2-mercaptoethyl)cyclohexane was prepared by
removing the acyl group. Into a 5 L, three-neck round bottomed
flask equipped with magnetic stir bar, temperature
probe/controller, heating mantle, addition funnel, distilling head
and condenser, and nitrogen inlet were charged
tris-(4-oxo-3-thiapentyl)cyclohexane (1,866 grams, 4.77 moles) and
absolute ethanol (1,219 grams, 26.5 moles). Sodium ethoxide in
ethanol (99 grams of 21% sodium ethoxide, purchased from Aldrich
Chemical) was added in five increments. The mixture was heated and
the ethanol and ethyl acetate were removed. Ethanol (785 grams) was
added and the ethyl acetate and ethanol were distilled from the
mixture at atmospheric pressure. Ethanol (1,022 grams) was added to
the mixture and the ethyl acetate, ethanol and low boiling
components were distilled form the mixture under reduced pressure
at 73.degree. C. The mercaptan intermediate (1,161 grams, 4.5
moles) was used in the next step for the synthesis. The yield was
93 percent.
The
bis-(2-mercaptoethyl)(6-triethylsilyl-3-thia-1-hexyl)cyclohexane
was prepared by reaction of the trimercaptan intermediate with
3-chloropropyltriethoxysilane. Into a 3 L, three-neck round
bottomed flask equipped with magnetic stir bar, temperature
probe/controller, heating mantle, addition funnel, condenser, air
inlet and a sodium hydroxide scrubber, was charged
1,2,4-tris-(2-mercaptoethyl)cyclohexane (450 grams, 1.7 moles).
Sodium ethoxide in ethanol (421 grams of 21% sodium ethoxide,
purchased from Aldrich Chemical) was added over two hours.
3-Chloropropyltriethoxysilane (410 grams, 1.7 moles) was added
slowly over a period of 2 hours and then heated at reflux for 14
hours. An additional aliquot of 3-chloropropyltriethoxysilane (42.5
grams, 0.18 mole) was added, heated for 2.5 hours at 79.degree. C.,
cooled and then filtered. The crude product was distilled under
reduced pressure. The fraction that boiled between 191 and
215.degree. C. was collected (343 grams, 0.73 mole) and used in the
next step of the synthesis. The product yield was 43 percent.
The product,
(6-triethoxysilyl-3-thia-1-hexyl)-bis-(7-triethoxysilyl
-3,4-dithiaheptyl)cyclohexane, was prepared by reacting the silated
dimercaptan intermediated with sulfur and
3-chloropropyltriethoxysilane. Into a 3 L, three-neck round
bottomed flask equipped with magnetic stir bar, temperature
probe/controller, heating mantle, addition funnel, distilling head
and condenser, and nitrogen inlet were charged
bis-(2-mercaptoethyl)(6-triethylsilyl-3-thia-1-hexyl)cyclohexane
(326 grams, 0.7 mole), sodium ethoxide in ethanol (451 grams of 21%
sodium ethoxide, purchased from Aldrich Chemical), sulfur powder
(45 grams, 1.4 moles) and absolute ethanol (352 grams) and refluxed
for 3 hours. 3-Chloropropyltriethoxysilane (336 grams, 1.4 moles)
was added, refluxed for 72 hours, cooled and filtered using a glass
fritted filter with a 25-50 micron pore size. The solids were
washed with toluene, the organic layers combined and stripped to
remove the lights. The final product (635 grams, 0.7 mole) was
analyzed by HPLC. The chromatograph, shown in FIG. 1, indicated a
mixture of monomeric and oligomeric products.
One isomer of
(6-triethoxysilyl-3-thia-1-hexyl)-bis-(7-triethoxysilyl-3,4-dithiaheptyl)-
cyclohexane has the following structure:
##STR00002##
Example 2
Preparation of
(6-triethoxysilyl-3-thia-1-hexyl)-bis-(9-triethoxysilyl-3,4,5,6-tetrathia-
nonyl)cyclohexane, related oligomers and
bis-(3-triethoxysilylpropyl) polysulfide mixture
The dimercaptan silane intermediate,
(6-triethoxysilyl-3-thia-1-hexyl)
-bis-(2-mercaptoethyl)cyclohexane, was prepared by the procedure
described in Example 1.
The product,
(6-triethoxysilyl-3-thia-1-hexyl)-bis-(9-triethoxysilyl
-3,4,5,6-tetrathianonyl)cyclohexane, related oligomers and
bis-(3-triethoxysilylpropyl)polysulfide mixture, was prepared by
reacting the dimercaptan silane with base, sulfur and
3-chloropropyltriethoxysilane. Into a 2 L, three-neck round
bottomed flask equipped with magnetic stir bar, temperature
probe/controller, heating mantle, addition funnel, distilling head
and condenser, and nitrogen inlet were charged
bis-(2-mercaptoethyl)(6-triethylsilyl-3-thia-1-hexyl)cyclohexane
(249.7 grams, 0.53 mole), sodium ethoxide in ethanol (345.2 grams
of 21% sodium ethoxide, purchased from Aldrich Chemical), sulfur
powder (102.5 grams, 3.2 moles) and absolute ethanol (250 grams)
and refluxed for 24 hours. 3-Chloropropyltriethoxysilane (256.5
grams, 1.07 moles) was added, refluxed for 72 hours, cooled and
then filtered using a 3.5 micron asbestocel filter. The final
product (487.4 grams, 0.47 mole, 88 percent yield) was analyzed by
HPLC. The chromatograph indicated a mixture of products.
One isomer of
(6-triethoxysilyl-3-thia-1-hexyl)-bis-(9-triethoxysilyl
-3,4,5,6-tetrathianonyl)cyclohexane has the following
structure:
##STR00003##
Comparative Examples A-C, Examples 3-5
The Use of Silanes in Low Rolling Resistant Tire Tread
Formulation.
A model low rolling resistance passenger tire tread formulation as
described in Table 1 and a mix procedure were used to evaluate
representative examples of the silanes of the present invention.
The silane in Example 2 was mixed as follows in a "B" BANBURY.RTM.
(Farrell Corp.) mixer with a 103 cu. in. (1,690 cc) chamber volume.
The mixing of the rubber was done in two steps. The mixer was
turned on with the mixer at 80 rpm and the cooling water at
71.degree. C. The rubber polymers were added to the mixer and ram
down mixed for 30 seconds. The silica and the other ingredients in
Masterbatch of Table 1 except for the silane and the oils were
added to the mixer and ram down mixed for 60 seconds. The mixer
speed was reduced to 35 rpm and then the silane and oils of the
Masterbatch were added to the mixer and ram down for 60 seconds.
The mixer throat was dusted down and the ingredients ram down mixed
until the temperature reached 149.degree. C. The ingredients were
then mixed for an addition 3 minutes and 30 seconds. The mixer
speed was adjusted to hold the temperature between 152 and
157.degree. C. The rubber was dumped (removed from the mixer), a
sheet was formed on a roll mill set at about 85.degree. C. to
88.degree. C., and then allowed to cool to ambient temperature.
In the second step, Masterbatch was recharged into the mixer. The
mixer's speed was 80 rpm, the cooling water was set at 71.degree.
C. and the batch pressure was set at 6 MPa. The Masterbatch was ram
down mixed for 30 seconds and then the temperature of the
Masterbatch was brought up to 149.degree. C., and then the mixer's
speed was reduce to 32 rpm and the rubber was mixed for 3 minutes
and 20 seconds at temperatures between 152 and 157.degree. C. After
mixing, the rubber was dumped (removed from the mixer), a sheet was
formed on a roll mill set at about 85.degree. C. to 88.degree. C.,
and then allowed to cool to ambient temperature.
The rubber Masterbatch and the curatives were mixed on a 15
cm.times.33 cm two roll mill that was heated to between 48.degree.
C. and 52.degree. C. The sulfur and accelerators were added to the
rubber (Masterbatch) and thoroughly mixed on the roll mill and
allowed to form a sheet. The sheet was cooled to ambient conditions
for 24 hours before it was cured. The curing condition was
160.degree. C. for 20 minutes. The silated cyclic core polysulfides
from Examples 1 and 2 were compounded into the tire tread
formulation according to the above procedure and their performance
was compared to the performance of silanes which are practiced in
the prior art, bis-(3-triethoxysilyl-1-propyl)disulfide (TESPD),
bis-(3-triethoxysilyl-1-propyl) tetrasulfide (TESPT) and
1,2,4-tris-(7-triethoxysilyl-3,4-dithiaheptyl)cyclohexane (TESHC),
Comparative Examples A-C. The test procedures were described in the
following ASTM methods:
TABLE-US-00001 Mooney Scorch ASTM D1646 Mooney Viscosity ASTM D1646
Oscillating Disc Rheometer (ODR) ASTM D2084 Storage Modulus, Loss
Modulus, ASTM D412 and D224 Tensile and Elongation DIN Abrasion DIN
Procedure 53516 Heat Buildup ASTM D623 Percent Permanent Set ASTM
D623 Shore A Hardness ASTM D2240
The results of this procedure are tabulated below in Table 1.
TESPD=bis-(3-triethoxysilylpropyl) disulfide
TESPT=bis-(3-triethoxysilylpropyl) tetrasulfide
TESHC=1,2,4-tris-(6-triethoxysilyl-3,4-dithiaheptyl)cyclohexane
TABLE-US-00002 TABLE 1 Example Number Ingredients Units Comp. Ex. A
Comp. Ex. B Comp. Ex. C Example 3 Example 4 Example 5 Masterbatch
SMR-10, natural rubber phr 10.00 10.00 10.00 10.00 10.00 10.00
Budene 1207, polybutadiene phr 35.00 35.00 35.00 35.00 35.00 35.00
Buna VSL 5025-1, oil-ext sSBR phr 75.63 75.63 75.63 75.63 75.63
75.63 N339, carbon black phr 12.00 12.00 12.00 12.00 12.00 12.00
Ultrasil VN3 GR, silica phr 85.00 85.00 85.00 85.00 85.00 85.00
Sundex 8125TN, process oil. phr 6.37 6.37 6.37 6.37 6.37 6.37
Erucical H102, rapeseed oil phr 5.00 5.00 5.00 5.00 5.00 5.00
Flexzone 7P, antiozonant phr 2.00 2.00 2.00 2.00 2.00 2.00 TMQ phr
2.00 2.00 2.00 2.00 2.00 2.00 Sunproof Improved, wax phr 2.50 2.50
2.50 2.50 2.50 2.50 Kadox 720 C, zinc oxide phr 2.50 2.50 2.50 2.50
2.50 2.50 Industrene R, stearic acid phr 1.00 1.00 1.00 1.00 1.00
1.00 Aktiplast ST, disperser phr 4.00 4.00 4.00 4.00 4.00 4.00
Silane TESPD phr 6.00 Silane TESPT phr 6.80 Silane TESHC phr 8.20
Silane, Example 1 phr 7.90 Silane, Example 2 phr 6 9 Catalysts
Naugex MBT phr 0.10 CBS phr 2.00 2.00 2.00 2.00 2.00 2.00 Diphenyl
guanidine phr 2.00 2.00 2.00 2.00 2.00 2.00 Rubbermakers sulfur 167
phr 2.20 2.20 2.20 2.20 2.20 2.20 Rubber Properties Mooney
Properties Viscosity at 100.degree. C., ML1 + 4 Mooney units 70 75
67 68 68.2 68.7 MV at 135.degree. C., MS1+ mooney units 32.4 37 30
34.6 33.2 34.5 Scorch at 135.degree. C., MS1 + t.sub.3 min. 14.2
8.1 13.2 7.3 8.1 5 Cure at 135.degree. C. MS1 + t.sub.18 min. 18.5
13.3 17.1 11.3 13.3 9.5 Rheometer (ODR) Properties, 1.degree. arc
at 149.degree. C. M.sub.L dN-m 8.9 10.1 8.4 8.6 8.6 9.1 M.sub.H
dN-m 34.9 38.9 38.5 35.9 32.9 37.9 t90 min. 18 17.1 14.5 11.5 17.4
13.5 Physical Properties, cured to t90 at 149.degree. C. Durometer
Shore "A" shore A 68 69 68 66 66 69 100% Modulus MPa 2.35 2.8 2.56
2.72 2.38 2.89 300% Modulus MPa 8.54 10.86 9.06 11.42 9.79 12.32
Reinforcement Index 3.63 3.88 3.54 4.2 4.11 4.26 Tensile MPa 18.95
18.19 16.97 21.57 22.36 22.13 Elongation % 582 448 492 505 590 500
Abrasion (DIN) mm.sup.3 144 145 158 132 138 135 Dynamic Properties
in cured state, 60.degree. C., simple shear - non-linearity (0-10%)
G'.sub.initial MPa 8.1 7.7 9 4.7 6.91 6.2 .DELTA. G' MPa 5.8 5.2
6.5 2.65 4.65 3.87 G''.sub.max MPa 1 0.91 1.07 0.53 0.786 0.66
tan.delta..sub.max 0.243 0.228 0.243 0.186 0.206 0.189
Table 1, listing Comparative Examples A-C and Examples 3-5,
presents the performance parameters of silated cyclic core
polysulfide of the present invention, bis-(3-triethoxysilylpropyl)
disulfide, bis-(3-triethoxysilylpropyl)tetrasulfide and
1,2,4-tris(6-triethoxysilyl-3,4-dithiaheptyl)cyclohexane. The
physical properties of the rubber compounded with silated cyclic
core polysulfides from Examples 1 and 2 are consistently and
substantially higher than the control silanes.
The silated cyclic core polysulfide of the present invention impart
higher performance to silica-filled elastomer compositions,
including better coupling of the silica to the rubber, as
illustrated by the higher reinforcement index. The better
reinforcing indices translate into performance improvements for the
elastomer compositions and articles manufactured from these
elastomers.
It is noted that the foregoing examples have been provided merely
for the purpose of explanation and are in no way to be construed as
limiting of the present invention. While the present invention has
been described with reference to exemplary embodiments, it is
understood that the words which have been used herein are words of
description and illustration, rather than words of limitation.
Changes may be made, within the purview of the appended claims, as
presently stated and as amended, without departing from the scope
and spirit of the present invention in its aspects. Although the
present invention has been described herein with reference to
particular means, materials and embodiments, the present invention
is not intended to be limited to the particulars disclosed herein;
rather, the present invention extends to all functionally
equivalent structures, methods and uses, such as are within the
scope of the appended claims.
* * * * *